Process and composition for conductive material removal by electrochemical mechanical polishing

ABSTRACT

Compositions and methods for processing a substrate having a conductive material layer disposed thereon are provided. In one embodiment, a composition for processing a substrate having a conductive material layer disposed thereon is provided which composition includes an acid based electrolyte, a chelating agent, a corrosion inhibitor, a passivating polymeric material, a pH adjusting agent, a solvent, and a pH between about 3 and about 10. The composition is used in a method to form a passivation layer on the conductive material layer, abrading the passivation layer to expose a portion of the conductive material layer, applying a bias to the substrate, and removing the conductive material layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part U.S. patent application Ser.No. 10/845,754, filed May 14, 2004, which application is acontinuation-in-part of U.S. patent application Ser. No. 10/608,404,filed Jun. 26, 2003, which application is a continuation-in-part of U.S.patent application Ser. No. 10/456,220, filed Jun. 6, 2003, whichapplication is a continuation-in-part U.S. patent application Ser. No.10/378,097, filed Feb. 26, 2003, now U.S. Pat. No. 7,128,825 whichapplication claims priority to the U.S. Provisional Patent ApplicationSer. No. 60/359,746, filed on Feb. 26, 2002, and which application is acontinuation-in-part of U.S. patent application Ser. No. 10/038,066,filed Jan. 3, 2002, now U.S. Pat. No. 6,811,680, issued on Nov. 2, 2004,which application claims priority to the U.S. Provisional PatentApplication Ser. No. 60/275,874, filed on Mar. 14, 2001; and theapplication is a continuation-in-part U.S. patent application Ser. No.11/074,274, filed Mar. 7, 2005, which application is a continuationapplication of U.S. patent application Ser. No. 10/141,459, filed May 7,2002, now U.S. Pat. No. 6,863,797, issued on Mar. 8, 2005, whichapplication is a continuation-in-part of U.S. patent application Ser.No. 10/032,275, filed Dec. 21, 2001 now U.S. Pat. No. 6,899,804; andeach application is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to compositions and methodsfor removing a conductive material from a substrate.

2. Background of the Related Art

Reliably producing sub-half micron and smaller features is one of thekey technologies for the next generation of very large scale integration(VLSI) and ultra large-scale integration (ULSI) of semiconductordevices. However, as the limits of circuit technology are pushed, theshrinking dimensions of interconnects in VLSI and ULSI technology haveplaced additional demands on processing capabilities. Reliable formationof interconnects is important to VLSI and ULSI success and to thecontinued effort to increase circuit density and quality of individualsubstrates and die.

Multilevel interconnects are formed using sequential material depositionand material removal techniques on a substrate surface to form featurestherein. As layers of materials are sequentially deposited and removed,the uppermost surface of the substrate may become non-planar across itssurface and require planarization prior to further processing.Planarization or “polishing” is a process in which material is removedfrom the surface of the substrate to form a generally even, planarsurface. Planarization is useful in removing excess deposited material,removing undesired surface topography, and surface defects, such assurface roughness, agglomerated materials, crystal lattice damage,scratches, and contaminated layers or materials to provide an evensurface for subsequent photolithography and other semiconductormanufacturing processes. One conventional process for planarization isby chemical mechanical polishing (CMP), which planarizes a layer bychemical activity and mechanical activity,

It is extremely difficult to planarize a metal surface, particularly acopper surface, as of a damascene inlay as shown in FIGS. 1A and 1B,with a high degree of surface planarity using a chemical mechanicalpolishing process. A damascene inlay formation process may includeetching feature definitions in an interlayer dielectric, such as asilicon oxide layer, sometimes including a barrier layer in the featuredefinition and on a surface of the substrate, and depositing a thicklayer of copper material on the substrate surface and any barrier layerif present. Chemical mechanically polishing the copper material toremove excess copper above the substrate surface often insufficientlyplanarizes the copper surface. Chemical mechanical polishing techniquesto completely remove the copper material often results in topographicaldefects, such as dishing and erosion that may affect subsequentprocessing of the substrate.

Dishing occurs when a portion of the surface of the inlaid metal of theinterconnection formed in the feature definitions in the interlayerdielectric is excessively polished, resulting in one or more concavedepressions, which may be referred to as concavities or recesses.Referring to FIG. 1A, a damascene inlay of lines 11 are formed bydepositing copper (Cu) or a copper alloy, in a damascene opening formedin interlayer dielectric 10, for example, silicon dioxide. While notshown, a barrier layer of a suitable material such as titanium (ortantalum) and/or titanium nitride (or tantalum nitride) for copper maybe deposited between the interlayer dielectric 10 and the inlaid metal12. Subsequent to planarization, a portion of the inlaid metal 12 may bedepressed by an amount D, referred to as the amount of dishing. Dishingis more likely to occur in wider or less dense features on a substratesurface.

Additionally, residual material may remain after a polishing process. Insuch instances a second polishing step or an overpolishing process maybe performed to remove the remaining material. However, such processesmay result in erosion, characterized by excessive polishing of the layernot targeted for removal, such as a dielectric layer surrounding a metalfeature. Referring to FIG. 1 B, a copper line 21 and dense array ofcopper lines 22 are inlaid in interlayer dielectric 20. The process topolish the copper lines 22 may result in loss, or erosion E, of thedielectric 20 between the metal lines 22. Erosion is observed to occurnear narrower or more dense features formed in the substrate surface.Modifying conventional copper CMP polishing techniques has resulted inless than desirable polishing rates and less than desirable polishingresults than commercially acceptable.

Therefore, there is a need for compositions and methods for removingconductive material, such as excess copper material, from a substratethat minimizes the formation of topographical defects to the substrateduring planarization.

SUMMARY OF THE INVENTION

In one embodiment, a composition for processing a substrate having aconductive material layer disposed thereon is provided which compositionincludes an acid based electrolyte, a chelating agent, a corrosioninhibitor, a passivating polymeric material, a pH adjusting agent, asolvent, and a pH between about 3 and about 10.

In another embodiment, a method of processing a substrate having aconductive material layer disposed thereon is provided which includesdisposing a substrate having a conductive material layer formed thereonin a process apparatus comprising a first electrode and a secondelectrode, wherein the substrate is in electrical contact with thesecond electrode, providing a polishing composition between the firstelectrode and the substrate, wherein the polishing composition comprisesan acid based electrolyte, a chelating agent, a corrosion inhibitor, apassivating polymeric material, a pH adjusting agent, a solvent, and apH between about 3 and about 10, contacting the substrate to a polishingarticle, providing relative motion between the substrate and thepolishing article, applying a bias between the first electrode and thesecond electrode, and removing conductive material from the substratesurface.

In another embodiment, a method of removing a conductive material layeris provided which includes providing the substrate to a processapparatus; exposing the substrate to a first polishing composition,contacting the substrate to a polishing article, providing relativemotion between the substrate and the polishing article, applying a firstbias to the substrate, removing at least 50% of the conductive materiallayer, exposing the substrate to a second polishing compositioncomprising an acid based electrolyte, a chelating agent, a corrosioninhibitor, a passivating polymeric material, a pH adjusting agent, a pHbetween about 3 and about 10, and a solvent, contacting the substrate tothe polishing article, providing relative motion between the substrateand the polishing article, applying a second bias to the substrate, andremoving the conductive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited aspects of the presentinvention are attained and can be understood in detail, a moreparticular description of embodiments of the invention, brieflysummarized above, may be had by reference to the embodiments thereofwhich are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIGS. 1A and 1B schematically illustrate the phenomenon of dishing anderosion respectively;

FIG. 2 is a plan view of an electrochemical mechanical planarizingsystem;

FIG. 3 is a sectional view of one embodiment of a first electrochemicalmechanical planarizing (ECMP) station of the system of FIG. 2;

FIG. 4A is a partial sectional view of the first ECMP station throughtwo contact assemblies;

FIGS. 4B-C are sectional views of alternative embodiments of contactassemblies;

FIGS. 4D-E are sectional views of plugs;

FIGS. 5A and 5B are side, exploded and sectional views of one embodimentof a contact assembly;

FIG. 6 is one embodiment of a contact element;

FIG. 7 is a vertical sectional view of another embodiment of an ECMPstation; and

FIGS. 8A-8D are schematic cross-sectional views illustrating a polishingprocess performed on a substrate according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In general, aspects of the inventions provide compositions and methodsfor removing at least a conductive material from a substrate surface.The inventions are described below in reference to a planarizing processfor the removal of conductive materials from a substrate surface by anelectrochemical mechanical polishing (ECMP) technique.

The words and phrases used herein should be given their ordinary andcustomary meaning in the art by one skilled in the art unless otherwisefurther defined. Chemical mechanical polishing should be broadlyconstrued and includes, but is not limited to, planarizing a substratesurface using chemical activity and mechanical activity, or a concurrentapplication of chemical activity and mechanical activity.Electropolishing should be broadly construed and includes, but is notlimited to, removing material from a substrate by eroding the substratesurface under application of electric current. Electrochemicalmechanical polishing (ECMP) should be broadly construed and includes,but is not limited to, planarizing a substrate by the application ofelectrochemical activity, mechanical activity, chemical activity, or aconcurrent application of a combination of electrochemical, chemical,and/or mechanical activity to remove material from a substrate surface.

Anodic dissolution should be broadly construed and includes, but is notlimited to, the application of an anodic bias to a substrate directly orindirectly which results in the removal of conductive material from asubstrate surface and into a surrounding polishing composition.Polishing composition should be broadly construed and includes, but isnot limited to, a composition that provides ionic conductivity, andthus, electrical conductivity, in a liquid medium, which generallycomprises materials known as electrolyte components. The amount of eachcomponent in the polishing compositions can be measured in volumepercent or weight percent. Volume percent refers to a percentage basedon volume of a desired liquid component divided by the total volume ofall of the liquid in the complete composition. A percentage based onweight percent is the weight of the desired component divided by thetotal weight of all of the liquid components in the completecomposition. Abrading and abrasion should be broadly construed andincludes, but is not limited to, contacting a material and displacing,disturbing, or removing all or a portion of the material.

The electrochemical mechanical polishing process may be performed in aprocess apparatus, such as a platform having one or more polishingstations adapted for electrochemical mechanical polishing processes. Aplaten for performing an electrochemical mechanical polishing processmay include a polishing article, a first electrode, and a secondelectrode, wherein the substrate is in electrical contact with thesecond electrode. A first electrochemical mechanical polishing processmay be performed on a first platen as described herein and the secondelectrochemical mechanical polishing process may be performed on thesame or different platen adapted for electrochemical mechanicalpolishing, such as the second platen as described herein.

Apparatus

FIG. 2 is a plan view of one embodiment of a planarization system 100having an apparatus for electrochemically processing a substrate. Theexemplary system 100 generally comprises a factory interface 102, aloading robot 104, and a planarizing module 106. The loading robot 104is disposed proximate the factory interface 102 and the planarizingmodule 106 to facilitate the transfer of substrates 122 therebetween.

A controller 108 is provided to facilitate control and integration ofthe modules of the system 100. The controller 108 comprises a centralprocessing unit (CPU) 110, a memory 112, and support circuits 114. Thecontroller 108 is coupled to the various components of the system 100 tofacilitate control of, for example, the planarizing, cleaning, andtransfer processes.

The factory interface 102 generally includes a cleaning module 116 andone or more wafer cassettes 118. An interface robot 120 is employed totransfer substrates 122 between the wafer cassettes 118, the cleaningmodule 116 and an input module 124. The input module 124 is positionedto facilitate transfer of substrates 122 between the planarizing module106 and the factory interface 102 by grippers, for example vacuumgrippers or mechanical clamps (not shown).

The planarizing module 106 includes at least a first electrochemicalmechanical planarizing (ECMP) station 128, disposed in anenvironmentally controlled enclosure 188. Examples of planarizingmodules 106 that can be adapted to benefit from the invention includeMIRRA® Chemical Mechanical Planarizing Systems, MIRRA MESA™ ChemicalMechanical Planarizing Systems, REFLEXION® Chemical MechanicalPlanarizing Systems, REFLEXION LK™ Chemical Mechanical PlanarizingSystems, and REFLEXION LK ECMP™ Chemical Mechanical Planarizing Systems,all available from Applied Materials, Inc. of Santa Clara, Calif. Otherplanarizing modules, including those that use processing pads,planarizing webs, or a combination thereof, and those that move asubstrate relative to a planarizing surface in a rotational, linear orother planar motion may also be adapted to benefit from the invention.

In the embodiment depicted in FIG. 2, the planarizing module 106includes one bulk ECMP station 128, a second ECMP station 130 and oneCMP station 132. Bulk removal of conductive material from the substrateis performed through an electrochemical dissolution process at the bulkECMP station 128. After the bulk material removal at the bulk ECMPstation 128, residual conductive material is removed from the substrateat the residual ECMP station 130 through a second electrochemicalmechanical process. It is contemplated that more than one residual ECMPstation 130 may be utilized in the planarizing module 106.

A conventional chemical mechanical planarizing process is performed atthe planarizing station 132 after processing at the residual ECMPstation 130 by the barrier removal process described herein.Alternatively, an example of a conventional CMP process on a chemicalmechanical polishing station for the barrier removal is described inU.S. patent Application Ser. No. 10/187,857, filed Jun. 27, 2002, whichis incorporated by reference in its entirety. It is contemplated thatother CMP processes may be alternatively performed. As the CMP stations132 are conventional in nature, further description thereof has beenomitted for the sake of brevity.

It is contemplated that more than one ECMP station may be utilized toperform the multi-step removal process after the bulk removal processperformed at a different station. Alternatively, each of the first andsecond ECMP stations 128, 130 may be utilized to perform both the bulkand multi-step conductive material removal on a single station. It isalso contemplated that all ECMP stations (for example 3 stations of themodule 106 depicted in FIG. 2) may be configured to process theconductive layer with a two step removal process.

The exemplary planarizing module 106 also includes a transfer station136 and a carousel 134 that are disposed on an upper or first side 138of a machine base 140. In one embodiment, the transfer station 136includes an input buffer station 142, an output buffer station 144, atransfer robot 146, and a load cup assembly 148. The input bufferstation 142 receives substrates from the factory interface 102 by meansof the loading robot 104. The loading robot 104 is also utilized toreturn polished substrates from the output buffer station 144 to thefactory interface 102. The transfer robot 146 is utilized to movesubstrates between the buffer stations 142, 144 and the load cupassembly 148.

In one embodiment, the transfer robot 146 includes two gripperassemblies (not shown), each having pneumatic gripper fingers that holdthe substrate by the substrate's edge. The transfer robot 146 maysimultaneously transfer a substrate to be processed from the inputbuffer station 142 to the load cup assembly 148 while transferring aprocessed substrate from the load cup assembly 148 to the output bufferstation 144. An example of a transfer station that may be used toadvantage is described in U.S. Pat. No. 6,156,124, issued Dec. 5, 2000to Tobin, which is herein incorporated by reference in its entirety.

The carousel 134 is centrally disposed on the base 140. The carousel 134typically includes a plurality of arms 150, each supporting aplanarizing head assembly 152. Two of the arms 150 depicted in FIG. 2are shown in phantom such that the transfer station 136 and aplanarizing surface 126 of the first ECMP station 128 may be seen. Thecarousel 134 is indexable such that the planarizing head assemblies 152may be moved between the planarizing stations 128, 130, 132 and thetransfer station 136. One carousel that may be utilized to advantage isdescribed in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov, etal., which is hereby incorporated by reference in its entirety.

A conditioning device 182 is disposed on the base 140 adjacent each ofthe planarizing stations 128, 130, 132. The conditioning device 182periodically conditions the planarizing material disposed in thestations 128, 130, 132 to maintain uniform planarizing results.

FIG. 3 depicts a sectional view of one of the planarizing headassemblies 152 positioned over one embodiment of the bulk ECMP station128. The planarizing head assembly 152 generally comprises a drivesystem 202 coupled to a planarizing head 204. The drive system 202generally provides at least rotational motion to the planarizing head204. The planarizing head 204 additionally may be actuated toward thebulk ECMP station 128 such that the substrate 122 retained in theplanarizing head 204 may be disposed against the planarizing surface 126of the bulk ECMP station 128 during processing. The drive system 202 iscoupled to the controller 108 that provides a signal to the drive system202 for controlling the rotational speed and direction of theplanarizing head 204.

In one embodiment, the planarizing head may be a TITAN HEAD™ or TITANPROFILER™ wafer carrier manufactured by Applied Materials, Inc.Generally, the planarizing head 204 comprises a housing 214 andretaining ring 224 that defines a center recess in which the substrate122 is retained. The retaining ring 224 circumscribes the substrate 122disposed within the planarizing head 204 to prevent the substrate fromslipping out from under the planarizing head 204 while processing. Theretaining ring 224 can be made of plastic materials such aspolyphenylene sulfide (PPS), polyetheretherketone (PEEK), and the like,or conductive materials such as stainless steel, Cu, Au, Pd, and thelike, or some combination thereof. It is further contemplated that aconductive retaining ring 224 may be electrically biased to control theelectric field during ECMP. Conductive or biased retaining rings tend toslow the polishing rate proximate the edge of the substrate. It iscontemplated that other planarizing heads may be utilized.

The first ECMP station 128 generally includes a platen assembly 230 thatis rotationally disposed on the base 140. The platen assembly 230 issupported above the base 140 by a bearing 238 so that the platenassembly 230 may be rotated relative to the base 140. An area of thebase 140 circumscribed by the bearing 238 is open and provides a conduitfor the electrical, mechanical, pneumatic, control signals andconnections communicating with the platen assembly 230.

Conventional bearings, rotary unions and slip rings, collectivelyreferred to as rotary coupler 276, are provided such that electrical,mechanical, fluid, pneumatic, control signals and connections may becoupled between the base 140 and the rotating platen assembly 230. Theplaten assembly 230 is typically coupled to a motor 232 that providesthe rotational motion to the platen assembly 230. The motor 232 iscoupled to the controller 108 that provides a signal for controlling forthe rotational speed and direction of the platen assembly 230.

A top surface 260 of the platen assembly 230 supports a processing padassembly 222 thereon. The processing pad assembly may be retained to theplaten assembly 230 by magnetic attraction, vacuum, clamps, adhesivesand the like.

A plenum 206 is defined in the platen assembly 230 to facilitate uniformdistribution of electrolyte to the planarizing surface 126. A pluralityof passages, described in greater detail below, are formed in the platenassembly 230 to allow electrolyte, provided to the plenum 206 from anelectrolyte source 248, to flow uniformly though the platen assembly 230and into contact with the substrate 122 during processing. It iscontemplated that different electrolyte compositions may be providedduring different stages of processing.

The processing pad assembly 222 includes an electrode 292 and at least aplanarizing portion 290. The electrode 292 is typically comprised of aconductive material, such as stainless steel, copper, aluminum, gold,silver and tungsten, among others. The electrode 292 may be solid,impermeable to electrolyte, permeable to electrolyte or perforated. Atleast one contact assembly 250 extends above the processing pad assembly222 and is adapted to electrically couple the substrate being processedon the processing pad assembly 222 to the power source 242. Theelectrode 292 is also coupled to the power source 242 so that anelectrical potential may be established between the substrate andelectrode 292.

A meter (not shown) is provided to detect a metric indicative of theelectrochemical process. The meter may be coupled or positioned betweenthe power source 242 and at least one of the electrode 292 or contactassembly 250. The meter may also be integral to the power source 242. Inone embodiment, the meter is configured to provide the controller 108with a metric indicative of processing, such a charge, current and/orvoltage. This metric may be utilized by the controller 108 to adjust theprocessing parameters in-situ or to facilitate endpoint or other processstage detection.

A window 246 is provided through the pad assembly 222 and/or platenassembly 230, and is configured to allow a sensor 254, positioned belowthe pad assembly 222, to sense a metric indicative of polishingperformance. For example, the sensor 704 may be an eddy current sensoror an interferometer, among other sensors. The metric, provided by thesensor 254 to the controller 108, provides information that may beutilized for processing profile adjustment in-situ, endpoint detectionor detection of another point in the electrochemical process. In oneembodiment, the sensor 254 an interferometer capable of generating acollimated light beam, which during processing, is directed at andimpinges on a side of the substrate 122 that is being polished. Theinterference between reflected signals is indicative of the thickness ofthe conductive layer of material being processed. One sensor that may beutilized to advantage is described in U.S. Pat. No. 5,893,796, issuedApr. 13, 1999, to Birang, et al., which is hereby incorporated byreference in its entirety.

Embodiments of the processing pad assembly 222 suitable for removal ofconductive material from the substrate 122 may generally include aplanarizing surface 126 that is substantially dielectric. Otherembodiments of the processing pad assembly 222 suitable for removal ofconductive material from the substrate 122 may generally include aplanarizing surface 126 that is substantially conductive. At least onecontact assembly 250 is provided to couple the substrate to the powersource 242 so that the substrate may be biased relative to the electrode292 during processing. Apertures 210, formed through the planarizinglayer 290 and the electrode 292 and the any elements disposed below theelectrode, allow the electrolyte to establish a conductive path betweenthe substrate 112 and electrode 292.

In one embodiment, the planarizing portion 290 of the processing padassembly 222 is a dielectric, such as polyurethane. Examples ofprocessing pad assemblies that may be adapted to benefit from theinvention are described in U.S. patent application Ser. No. 10/455,941,filed Jun. 6, 2003, entitled “Conductive Planarizing Article ForElectrochemical Mechanical Planarizing”, and U.S. patent applicationSer. No. 10/455,895, filed Jun. 6, 2003, entitled “ConductivePlanarizing Article For Electrochemical Mechanical Planarizing,” both ofwhich are hereby incorporated by reference in their entireties.

FIG. 4A is a partial sectional view of the first ECMP station 128through two contact assemblies 250, and FIGS. 5A-C are side, explodedand sectional views of one of the contact assemblies 250 shown in FIG.5A. The platen assembly 230 includes at least one contact assembly 250projecting therefrom and coupled to the power source 242 that is adaptedto bias a surface of the substrate 122 during processing. The contactassemblies 250 may be coupled to the platen assembly 230, part of theprocessing pad assembly 222, or a separate element. Although two contactassemblies 250 are shown in FIG. 3A, any number of contact assembliesmay be utilized and may be distributed in any number of configurationsrelative to the centerline of the platen assembly 230.

The contact assemblies 250 are generally electrically coupled to thepower source 242 through the platen assembly 230 and are movable toextend at least partially through respective apertures 368 formed in theprocessing pad assembly 222. The positions of the contact assemblies 250may be chosen to have a predetermined configuration across the platenassembly 230. For predefined processes, individual contact assemblies250 may be repositioned in different apertures 368, while apertures notcontaining contact assemblies may be plugged with a stopper 392 orfilled with a nozzle 394 (as shown in FIGS. 4D-E) that allows flow ofelectrolyte from the plenum 206 to the substrate. One contact assemblythat may be adapted to benefit from the invention is described in U.S.patent application Ser. No. 10/445,239, filed May 23, 2003, byButterfield, et al., and is hereby incorporated by reference in itsentirety.

Although the embodiments of the contact assembly 250 described belowwith respect to FIG. 4A depicts a rolling ball contact, the contactassembly 250 may alternatively comprise a structure or assembly having aconductive upper layer or surface suitable for electrically biasing thesubstrate 122 during processing. For example, as depicted in FIG. 4B,the contact assembly 250 may include a pad structure 350 having an upperlayer 352 made from a conductive material or a conductive composite(i.e., the conductive elements are dispersed integrally with or comprisethe material comprising the upper surface), such as a polymer matrix 354having conductive particles 356 dispersed therein or a conductive coatedfabric, among others. The pad structure 350 may include one or more ofthe apertures 210 formed therethrough for electrolyte delivery to theupper surface of the pad assembly. Other examples of suitable contactassemblies are described in U.S. Provisional Patent Application Ser. No.60/516,680, filed Nov. 3, 2003, by Hu, et al., which is herebyincorporated by reference in its entirety.

In one embodiment, each of the contact assemblies 250 includes a hollowhousing 302, an adapter 304, a ball 306, a contact element 314 and aclamp bushing 316. The ball 306 has a conductive outer surface and ismovably disposed in the housing 302. The ball 306 may be disposed in afirst position having at least a portion of the ball 306 extending abovethe planarizing surface 126 and at least a second position where theball 306 is substantially flush with the planarizing surface 126. It isalso contemplated that the ball 306 may move completely below theplanarizing surface 126. The ball 306 is generally suitable forelectrically coupling the substrate 122 to the power source 242. It iscontemplated that a plurality of balls 306 for biasing the substrate maybe disposed in a single housing 358 as depicted in FIG. 4C.

The power source 242 generally provides a positive electrical bias tothe ball 306 during processing. Between planarizing substrates, thepower source 242 may optionally apply a negative bias to the ball 306 tominimize attack on the ball 306 by process chemistries.

The housing 302 is configured to provide a conduit for the flow ofelectrolyte from the source 248 to the substrate 122 during processing.The housing 302 is fabricated from a dielectric material compatible withprocess chemistries. A seat 326 formed in the housing 302 prevents theball 306 from passing out of the first end 308 of the housing 302. Theseat 326 optionally may include one or more grooves 348 formed thereinthat allow fluid flow to exit the housing 302 between the ball 306 andseat 326. Maintaining fluid flow past the ball 306 may minimize thepropensity of process chemistries to attack the ball 306.

The contact element 314 is coupled between the clamp bushing 316 and theadapter 304. The contact element 314 is generally configured toelectrically connect the adapter 304 and ball 306 substantially orcompletely through the range of ball positions within the housing 302.In one embodiment, the contact element 314 may be configured as a springform.

In the embodiment depicted in FIGS. 4A-E and 5A-C and detailed in FIG.6, the contact element 314 includes an annular base 342 having aplurality of flexures 344 extending therefrom in a polar array. Theflexure 344 is generally fabricated from a resilient and conductivematerial suitable for use with process chemistries. In one embodiment,the flexure 344 is fabricated from gold plated beryllium copper.

Returning to FIGS. 4A and 5A-B, the clamp bushing 316 includes a flaredhead 424 having a threaded post 422 extending therefrom. The clampbushing 316 may be fabricated from either a dielectric or conductivematerial, or a combination thereof, and in one embodiment, is fabricatedfrom the same material as the housing 302. The flared head 424 maintainsthe flexures 344 at an acute angle relative to the centerline of thecontact assembly 250 so that the flexures 344 of the contact elements314 are positioned to spread around the surface of the ball 306 toprevent bending, binding and/or damage to the flexures 344 duringassembly of the contact assembly 250 and through the range of motion ofthe ball 306.

The ball 306 may be solid or hollow and is typically fabricated from aconductive material. For example, the ball 306 may be fabricated from ametal, conductive polymer or a polymeric material filled with conductivematerial, such as metals, conductive carbon or graphite, among otherconductive materials. Alternatively, the ball 306 may be formed from asolid or hollow core that is coated with a conductive material. The coremay be non-conductive and at least partially coated with a conductivecovering.

The ball 306 is generally actuated toward the planarizing surface 126 byat least one of spring, buoyant or flow forces. In the embodimentdepicted in FIG. 5, flow through the passages formed through the adapter304 and clamp bushing 316 and the platen assembly 230 from theelectrolyte source 248 urge the ball 306 into contact with the substrateduring processing.

FIG. 7 is a sectional view of one embodiment of the second ECMP station130. The first and third ECMP stations 128, 132 may be configuredsimilarly. The second ECMP station 130 generally includes a platen 602that supports a fully conductive processing pad assembly 604. The platen602 may be configured similar to the platen assembly 230 described aboveto deliver electrolyte through the processing pad assembly 604, or theplaten 602 may have a fluid delivery arm (not shown) disposed adjacentthereto configured to supply electrolyte to a planarizing surface of theprocessing pad assembly 604. The platen assembly 602 includes at leastone of a meter or sensor 254 (shown in FIG. 3) to facilitate endpointdetection.

In one embodiment, the processing pad assembly 604 includes interposedpad 612 sandwiched between a conductive pad 610 and an electrode 614.The conductive pad 610 is substantially conductive across its topprocessing surface and is generally made from a conductive material or aconductive composite (i.e., the conductive elements are dispersedintegrally with or comprise the material comprising the planarizingsurface), such as a polymer matrix having conductive particles dispersedtherein or a conductive coated fabric, among others. The conductive pad610, the interposed pad 612, and the electrode 614 may be fabricatedinto a single, replaceable assembly. The processing pad assembly 604 isgenerally permeable or perforated to allow electrolyte to pass betweenthe electrode 614 and top surface 620 of the conductive pad 610. In theembodiment depicted in FIG. 7, the processing pad assembly 604 isperforated by apertures 622 to allow electrolyte to flow therethrough.In one embodiment, the conductive pad 610 is comprised of a conductivematerial disposed on a polymer matrix disposed on a conductive fiber,for example, tin particles in a polymer matrix disposed on a wovencopper coated polymer. The conductive pad 610 may also be utilized forthe contact assembly 250 in the embodiment of FIG. 3.

A conductive foil 616 may additionally be disposed between theconductive pad 610 and the subpad 612. The foil 616 is coupled to apower source 242 and provides uniform distribution of voltage applied bythe source 242 across the conductive pad 610. In embodiments notincluding the conductive foil 616, the conductive pad 610 may be coupleddirectly, for example, via a terminal integral to the pad 610, to thepower source 242. Additionally, the pad assembly 604 may include aninterposed pad 618, which, along with the foil 616, provides mechanicalstrength to the overlying conductive pad 610. Examples of suitable padassemblies are described in the previously incorporated U.S. patentapplication Ser. No. 10/455,941 and 10/455,895.

Polishing Processes

Methods are provided for polishing a substrate to remove residues andminimize dishing within features, while increasing throughput with adecrease in polishing time. The methods may be performed by anelectrochemical polishing technique, which includes a combination ofchemical activity, mechanical activity and electrical activity to removeconductive materials and planarize a substrate surface. The polishingcompositions described herein form passivation layers on the substratesurface. The passivation layer may chemically and/or electricallyinsulate material disposed on a substrate surface.

In one aspect, the method may include processing a substrate having aconductive material layer disposed over features, supplying a firstpolishing composition, or bulk polishing composition, to the surface ofthe substrate, applying a first pressure between the substrate and apolishing article, providing relative motion between the substrate andthe polishing article, applying a first bias between a first electrodeand a second electrode in electrical contact with the substrate,removing a portion, such as at least about 50%, of the conductivematerial, supplying a second polishing composition, or residualpolishing composition, to the surface of the substrate, applying asecond pressure between the substrate and a polishing article, providingrelative motion between the substrate and the polishing article,applying a second bias between a first electrode and a second electrodein electrical contact with the substrate, and removing residualconductive material from the substrate surface.

The removal of excess copper may be performed in one or more processingsteps, for example, a single copper removal step or a bulk copperremoval step and a residual copper removal step. Bulk material isbroadly defined herein as any material deposited on the substrate in anamount more than sufficient to substantially fill features formed on thesubstrate surface. Residual material is broadly defined as any materialremaining after one or more bulk or residual polishing process steps.Generally, in a two step process, the bulk removal during a firstelectrochemical mechanical polishing process removes at least about 50%of the conductive layer, preferably at least about 70%, more preferablyat least about 80%, for example, at least about 90%. The residualremoval during a second electrochemical mechanical polishing processremoves most, if not all the remaining conductive material disposed onthe barrier layer to leave behind the filled plugs.

The bulk removal electrochemical mechanical polishing process may beperformed on a first polishing platen and the residual removalelectrochemical mechanical polishing process on a second polishingplaten of the same or different polishing apparatus as the first platen.In another embodiment of the two-step process, the residual removalelectrochemical mechanical polishing process may be performed on thesame platen with the bulk removal process. Any barrier material may beremoved on a separate platen, such as the third platen in the apparatusdescribed in FIG. 2. For example, the apparatus described above inaccordance with the processes described herein may include three platensfor removing copper material including, for example, a first platen toremove bulk material, a second platen for residual removal and a thirdplaten for barrier removal and/or buffing the substrate surface. In suchan apparatus, the bulk and the residual processes are electrochemicalmechanical polishing processes and the barrier removal is a CMP processor another electrochemical mechanical polishing process. In anotherembodiment, three electrochemical mechanical polishing platens may beused to remove bulk material, residual removal and barrier removal.

While the following processes and compositions are described forremoving copper, the invention contemplates that the compositions andprocesses herein also may be used for the removal of other conductivematerials, such as aluminum, platinum, tungsten, titanium, titaniumnitride, tantalum, tantalum nitride, cobalt, gold, silver, ruthenium andcombinations thereof.

FIGS. 8A-8D are schematic cross-sectional views illustrating a polishingprocess performed on a substrate according to one embodiment forplanarizing a substrate surface described herein. A firstelectrochemical mechanical polishing process may be used to remove bulkcopper material from the substrate surface as shown from FIGS. 8A-8B andthen a second electrochemical mechanical polishing process to removeresidual copper materials as shown from FIGS. 8B-8C. Subsequentprocesses, such as barrier removal and buffering are used to produce thestructure shown in FIG. 8D. The first electrochemical mechanicalpolishing process produces to a fast removal rate of the copper layerand the second electrochemical mechanical polishing process, due to theprecise removal of the remaining copper material, and forms levelsubstrate surfaces with reduced or minimal dishing and erosion ofsubstrate features.

FIG. 8A is a schematic cross-sectional view illustrating one embodimentof a first electrochemical mechanical polishing process for removal ofbulk copper material. The substrate is disposed in an apparatuscontaining a first electrode. The substrate 800 has a dielectric layer810 patterned with narrow feature definitions 820 and wide featuredefinitions 830. Narrow feature definitions 820 and wide featuredefinitions 830 have a barrier material 840, for example, titaniumand/or titanium nitride, or alternatively, tantalum and/or tantalumnitride, deposited therein followed by a fill of a conductive material860, for example, copper. The deposition profile of the excess materialincludes a high overburden 870, also referred to as a hill or peak,formed over narrow feature definitions 820 and a minimal overburden 880,also referred to as a valley, formed over wide feature definitions 830.

The terms narrow and wide feature definitions may vary depending on thestructures formed on the substrate surface, but can generally becharacterized by the respective deposition profiles of excessivematerial deposition (or high overburden) formed over narrow featuredefinitions and minimal or low material deposition (minimal or lowoverburden), over wide feature definitions. For example narrow featuredefinitions may be about 0.13 μm in size and may have a high overburdenas compared to wide feature definitions that may be about 10 μm in sizeand that may have minimal or insufficient overburden. However, highoverburdens and low overburdens do not necessarily have to form overfeatures, but may form over areas on the substrate surface betweenfeatures.

The dielectric layer 810 may comprise one or more dielectric materialsconventionally employed in the manufacture of semiconductor devices. Forexample, dielectric materials may include materials such as silicondioxide, phosphorus-doped silicon glass (PSG), boron-phosphorus-dopedsilicon glass (BPSG), and silicon dioxide derived from tetraethylorthosilicate (TEOS) or silane by plasma enhanced chemical vapordeposition (PECVD). The dielectric layer may also comprise lowdielectric constant materials, including fluoro-silicon glass (FSG),polymers, such as polyamides, carbon-containing silicon oxides, such asBlack Diamond™ dielectric material, silicon carbide materials, which maybe doped with nitrogen and/or oxygen, including BLOK™ dielectricmaterials, available from Applied Materials, Inc. of Santa Clara, Calif.

A barrier layer 840 is disposed conformally in the feature definitions820 and 830 and on the substrate 800. The barrier layer 840 may comprisemetals or metal nitrides, such as tantalum, tantalum nitride, tantalumsilicon nitride, titanium, titanium nitride, titanium silicon nitride,tungsten, tungsten nitride and combinations thereof, or any othermaterial that may limit diffusion of materials between the substrateand/or dielectric materials and any subsequently deposited conductivematerials.

A conductive material layer 860 is disposed on the barrier layer 840.The term “conductive material layer” as used herein is defined as anyconductive material, such as copper, tungsten, aluminum, and/or theiralloys used to fill a feature to form lines, contacts or vias. While notshown, a seed layer of a conductive material may be deposited on thebarrier layer prior to the deposition of the conductive material layer860 to improve interlayer adhesion and improve subsequent depositionprocesses. The seed layer may be of the same material as the subsequentmaterial to be deposited.

One type of conductive material layer 860 comprises copper containingmaterials. Copper containing materials include copper, copper alloys(e.g., copper-based alloys containing at least about 80 weight percentcopper) or doped copper. As used throughout this disclosure, the phrase“copper containing material,” the word “copper,” and the symbol “Cu” areintended to encompass copper, copper alloys, doped copper, andcombinations thereof. Additionally, the conductive material may compriseany conductive material used in semiconductor manufacturing processing.

In the first electrochemical mechanical polishing step, a firstpassivation layer 885 is formed from exposure of the conductive materialto the bulk polishing composition. The first passivation layer 885 formson the exposed conductive material 860 on the substrate surfaceincluding the high overburden 870, peaks, and minimal overburden 880,valleys, formed in the deposited conductive material 860. The firstpassivation layer 885 chemically and/or electrically insulates thesurface of the substrate from chemical and/or electrical reactions.

The process begins with a substrate being positioned in a polishingapparatus, such as the apparatus descried herein and shown in FIG. 3. Afirst, or bulk removal, polishing composition as described herein isprovided to the substrate surface. The first polishing composition maybe provided at a flow rate between about 50 and about 800 millilitersper minute, such as about 300 milliliters per minute, to the substratesurface. The conductive material exposed to a polishing compositionresults in the formation of the first passivation layer 885 on theconductive material layer 860.

An example of the first polishing composition for the bulk removal stepincludes between about 1 wt % and about 10 wt % of phosphoric acid,between about 0.1 wt % and about 6 wt % of the at least one chelatingagent, between about 0.01 wt % and about 1 wt % of the corrosioninhibitor, between about 0.5 wt % and about 10 wt % of an inorganic ororganic salt, between about 0.2 wt % and about 5 wt % of an oxidizer,and between about 0.05 wt % and about 1 wt % of abrasive particulates.The composition has a conductivity of between about 60 and about 64milliSiemens/centimeter (mS/cm). Alternatively, first electrochemicalmechanical polishing step may comprise the second electrochemicalmechanical polishing composition as described herein. The process mayalso be performed with a composition temperature between about 20° C.and about 60° C.

A polishing article coupled to a polishing article assembly containing asecond electrode is then physically contacted and/or electricallycoupled with the substrate through a conductive polishing article. Thesubstrate surface and polishing article are contacted at a pressure lessthan about 2 pounds per square inch (lb/in² or psi) (13.8 kPa). Thecontact pressure may include a pressure of about 1 psi (6.9 kPa) orless, for example, between about 0.01 psi (69 Pa) and about 1 psi (6.9kPa), such as between about 0.1 (0.7 kPa) psi and about 0.8 psi (5.5kPa) or between about 0.1 (0.7 kPa) psi and less than about 0.5 psi (3.4kPa). In one aspect of the process, a pressure of about 0.3 psi (2.1kPa) or less is used.

Relative motion is provided between the substrate surface and theconductive article 203 to reduce or remove the first passivation layer885. Relative motion is provided between the substrate surface and theconductive pad assembly 222. The conductive pad assembly 222 disposed onthe platen is rotated at a platen rotational rate of between about 7 rpmand about 80 rpm, for example, about 28 rpm, and the substrate disposedin a carrier head is rotated at a carrier head rotational rate betweenabout 7 rpm and about 80 rpm, for example, about 37 rpm. The respectiverotational rates of the platen and carrier head are believed to providereduced shear forces and frictional forces when contacting the polishingarticle and substrate. Both the carrier head rotational speed and theplaten rotational speed may be between about 7 rpm and less than 40 rpm.In one aspect of bulk polishing process, the carrier head rotationalspeed may be greater than a platen rotational speed by a ratio ofcarrier head rotational speed to platen rotational speed of greater thanabout 1:1, such as a ratio of carrier head rotational speed to platenrotational speed between about 1.5:1 and about 12:1, for example betweenabout 1.5:1 and about 3:1, to remove material from the substratesurface.

A first bias from a power source 242 is applied between the twoelectrodes. The bias may be transferred from a conductive pad and/orelectrode in the polishing article assembly 222 to the substrate 208.The bias may be applied by an electrical pulse modulation techniqueproviding at least anodic dissolution.

The first bias is generally provided to produce anodic dissolution ofthe conductive material from the surface of the substrate at a currentdensity up and about 100 mA/cm² which correlates to an applied currentof about 40 amps to process substrates with a diameter up and about 300mm. For example, a 200 mm diameter substrate may have a current densitybetween about 0.01 mA/cm² and about 50 mA/cm², which correlates to anapplied current between about 0.01 A and about 20 A. The invention alsocontemplates that the bias may be applied and monitored by volts, ampsand watts. For example, in one embodiment, the power supply may apply apower between about 0.01 watts and 100 watts, a voltage between about0.01 V and about 10 V, and a current between about 0.01 amps and about10 amps. The bias between about 2.6 volts and about 3.5 volts, such as 3volts, may be used as the applied bias in the first electrochemicalprocessing step.

The first bias may be varied in power and application depending upon theuser requirements in removing material from the substrate surface. Forexample, increasing power application has been observed to result inincreasing anodic dissolution. The bias may also be applied by anelectrical pulse modulation technique. Pulse modulation techniques mayvary, but generally include a cycle of applying a constant currentdensity or voltage for a first time period, then applying no currentdensity or voltage or a constant reverse current density or voltage fora second time period. The process may then be repeated for one or morecycles, which may have varying power levels and durations. The powerlevels, the duration of power, an “on” cycle, and no power, an “off”cycle” application, and frequency of cycles, may be modified based onthe removal rate, materials to be removed, and the extent of thepolishing process. For example, increased power levels and increasedduration of power being applied have been observed to increase anodicdissolution.

In one pulse modulation process for electrochemical mechanicalpolishing, the pulse modulation process comprises an on/off powertechnique with a period of power application, “on”, followed by a periodof no power application, “off”. The on/off cycle may be repeated one ormore times during the polishing process. The “on” periods allow forremoval of exposed conductive material from the substrate surface andthe “off” periods allow for polishing composition components andby-products of “on” periods, such as metal ions, to diffuse to thesurface and complex with the conductive material. During a pulsemodulation technique process it is believed that the metal ions migrateand interact with the corrosion inhibitors and/or chelating agents byattaching to the passivation layer in the non-mechanically disturbedareas. The process thus allows etching in the electrochemically activeregions, not covered by the passivation layer, during an “on”application, and then allowing reformation of the passivation layer insome regions and removal of excess material during an “off” portion ofthe pulse modulation technique in other regions. Thus, control of thepulse modulation technique can control the removal rate and amount ofmaterial removed from the substrate surface.

The “on” “off” period of time may be between about 1 second and about 60seconds each, for example, between about 2 seconds and about 25 seconds,and the invention contemplates the use of pulse techniques having “on”and “off” periods of time greater and shorter than the described timeperiods herein. In one example of a pulse modulation technique, power isapplied between about 16% and about 66% of each cycle.

Non-limiting examples of pulse modulation technique with an on/off cyclefor electrochemical mechanical polishing of materials described hereininclude: applying power, “on”, between about 5 seconds and about 10seconds and then not applying power, “off”, between about 2 seconds andabout 25 seconds; applying power for about 10 seconds and not applyingpower for 5 seconds, or applying power for 10 seconds and not applyingpower for 2 seconds, or even applying power for 5 seconds and notapplying power for 25 seconds to provide the desired polishing results.The cycles may be repeated as often as desired for each selectedprocess. One example of a pulse modulation process is described incommonly assigned U.S. Pat. No. 6,379,223, which is incorporated byreference herein to the extent not inconsistent with the claimed aspectsand disclosure herein. Further examples of pulse modulation processesare described in co-pending U.S. patent application Ser. No. 10/611,805,entitled “Effective Method To Improve Surface Finish InElectrochemically Assisted Chemical Mechanical Polishing”, filed on Jun.30, 2003, which is incorporated by reference herein to the extent notinconsistent with the claimed aspects and disclosure herein.

A removal rate of conductive material of up and about 15,000 Å/min canbe achieved by the processes described herein. Higher removal rates aregenerally desirable, but due to the goal of maximizing processuniformity and other process variables (e.g., reaction kinetics at theanode and cathode) it is common for dissolution rates to be controlledbetween about 100 Å/min and about 15,000 Å/min. In one embodiment of theinvention where the copper material to be removed is less than 5,000 Åthick, the voltage (or current) may be applied to provide a removal ratebetween about 100 Å/min and about 5,000 Å/min. The substrate istypically exposed to the polishing composition and power application fora period of time sufficient to remove at least a portion or all of thedesired material disposed thereon.

The first passivation layer is formed from the exposure of the substratesurface to the corrosion inhibitor and/or other materials capable offorming a passivating or insulating film, for example, chelating agents.The thickness and density of the passivation layer can dictate theextent of chemical reactions and/or amount of anodic dissolution. Forexample, a thicker or denser passivation layer 885 has been observed toresult in less anodic dissolution compared to thinner and less densepassivation layers. Thus, control of the composition of passivatingagents, corrosion inhibitors and/or chelating agents, allow control ofthe removal rate and amount of material removed from the substratesurface

During anodic dissolution under application of the bias, the substratesurface, i.e., the conductive material layer 860 may be biasedanodically above a threshold potential of the conductive material, forexample, a metal material, on the substrate surface to “oxidize”. When ametal material oxidizes, a metal atom gives up one or more electrons tothe power source and forms metal ions or cations. The metal ions maythen leave the substrate surface and dissolve into the electrolytesolution. In the case where copper is the desired material to beremoved, cations can have the Cu¹⁺ or Cu²⁺ oxidation state.

The metal ions may also contribute to the formation of the thicknessand/or density of the first passivation layer 885. For example, theinhibitors and/or chelating agents found in the polishing compositionmay complex with the metal ions and the metal ions become incorporatedinto the first passivation layer 885. Thus, the presence of theinhibitors and/or chelating agents found in the polishing compositionlimit or reduce the electrochemical dissolution process of the metalions into the electrolyte, and further incorporate such metal ions intothe first passivation layer 885. It has been observed that the thicknessand/or density of the undisturbed portion of the first passivation layer885 may increase after periods of applied bias for anodic dissolution ofconductive materials on the substrate surface. It is believed that theincrease in the thickness and/or density of the undisturbed portion ofthe first passivation layer 885 is related to the total applied powerand is a function of time and/or power levels. It has also been observedthat the undisturbed portion of the passivation layer 885 incorporatesmetal ions and that the metal ions may contribute to the thicknessand/or density of the passivation layer.

Mechanical abrasion by a conductive polishing article removes the firstpassivation layer 885 that insulates the conductive material chemicallyand/or electrically. For example, the first passivation layer suppressesthe current for anodic dissolution so that areas of high overburden ispreferentially removed over areas of minimal overburden as thepassivation layer is retained in areas of minimal or no contact with theconductive polishing article 203. The removal rate of the conductivematerial 860 covered by the first passivation layer 885 is less than theremoval rate of conductive material without the first passivation layer885. As such, the excess material disposed over narrow featuredefinitions 820 and the substrate field 850 is removed at a higher ratethan over wide feature definitions 830 still covered by the firstpassivation layer 885.

The polishing pressures used herein reduce or minimize damaging shearforces and frictional forces for substrates containing low k dielectricmaterials. Reduced or minimized forces can result in reduced or minimaldeformations and defect formation of features from polishing. Further,the lower shear forces and frictional forces have been observed toreduce or minimize formation of topographical defects, such as erosionof dielectric materials and dishing of conductive materials as well asreducing delamination, during polishing. Contact between the substrateand a conductive polishing article also allows for electrical contactbetween the power source and the substrate by coupling the power sourceto the polishing article when contacting the substrate.

Residual material is removed with a second electrochemical mechanicalpolishing process. The second electrochemical mechanical polishingprocess provides a reduced removal rate compared to the firstelectrochemical mechanical polishing process step in order to preventexcess metal removal from forming topographical defects, such asconcavities or depressions known as dishing D, as shown in FIG. 1A, anderosion E as shown in FIG. 1B as well as reducing delamination duringpolishing. Therefore, a majority of the conductive layer 860 is removedat a faster rate during the first electrochemical mechanical polishingprocess than the remaining or residual conductive layer 860 during thesecond electrochemical mechanical polishing process. The two-stepelectrochemical mechanical polishing process increases throughput of thetotal substrate processing while producing a smooth surface with littleor no defects.

FIG. 8B illustrates the initiation of the second electrochemicalmechanical polishing step after at least about 50% of the conductivematerial 860 was removed after the bulk removal of the firstelectrochemical mechanical polishing process, for example, about 90%.After the first electrochemical mechanical polishing process, conductivematerial 860 may still include the high overburden 870, peaks, and/orminimal overburden 880, valleys, but with a reduced proportional size.However, conductive material 860 may also be rather planar across thesubstrate surface (not pictured).

In the second electrochemical mechanical polishing step, a secondpassivation layer 890 is formed from exposure of the conductive materialto the residual polishing composition. The second passivation layer 890forms on the exposed conductive material 860 on the substrate surface.The second passivation layer 890 chemically and/or electricallyinsulates the surface of the substrate from chemical and/or electricalreactions.

A second, or residual removal, polishing composition as described hereinfor residual material removal is provided to the substrate surface. Thepolishing composition may be provided at a flow rate between about 50and about 800 milliliters per minute, such as about 300 milliliters perminute, to the substrate surface.

An example of the second polishing composition for the residual removalstep includes between about 1 vol % and about 10 vol % of an acid basedelectrolyte, between about 0.1 wt % and about 6 wt % of a chelatingagent, between about 0.01 wt % and about 1 wt % of a corrosioninhibitor, between about 0.001 vol % and about 2 vol % of a passivatingpolymeric material, between about 1 wt. % and about 20 wt. % of a pHadjusting agent, a solvent, and a pH between about 4 and about 7. Theresidual composition has a conductivity of between about 20 and about 80milliSiemens/centimeter (mS/cm), for example, between about 30 and about60 milliSiemens/centimeter (mS/cm). A further example of a polishingcomposition includes about 6 vol % of phosphoric acid, about 2 wt. % ofammonium citrate, about 0.3 wt. % of benzotriazole, about 0.05 vol % ofXP-1296, about 0.025 vol % of 750000 molecular weight Polyethylene imine(PEI), deionized water, and sufficient potassium hydroxide to provide apH of about 5.75, and a conductivity of about 54 mS/cm.

The mechanical abrasion in the above residual removal process isperformed at the first electrochemical mechanical polishing process stepcontact pressure of less than about 2 pounds per square inch (lb/in² orpsi) (13.8 kPa) between the polishing pad and the substrate. Removal ofthe conductive material 860 may be performed with a process having apressure of about 1 psi (6.9 kPa) or less, for example, between about0.01 psi (69 Pa) and about 1 psi (6.9 kPa), such as between about 0.1(0.7 kPa) psi and about 0.8 psi (5.5 kPa). In one aspect of the process,a pressure of about 0.3 psi (2.1 kPa) or less is used. Alternatively,the pressure of the second electrochemical mechanical polishing step maybe reduced compared to the first electrochemical mechanical polishingstep to further reduce the removal rate of the copper material. Contactbetween the substrate and a conductive polishing article also allows forelectrical contact between the power source and the substrate bycoupling the power source to the polishing article when contacting thesubstrate.

Relative motion is provided between the substrate surface and theconductive pad assembly 222, preferably a fully conductive pad assemblyshould be assembly 620 as shown in FIG. 7. A fully conductive polishingpad assembly may be used to improve the residual removal efficiency ofthe copper material. The conductive pad assembly disposed on the platenis rotated at a rotational rate of between about 7 rpm and about 80 rpm,such as between about 7 rpm and about 50 rpm, for example, about 20 rpm,and the substrate disposed in a carrier head is rotated at a rotationalrate between about 7 rpm and about 80 rpm, such as between about 7 rpmand about 70 rpm, for example, about 21 rpm. In one aspect of the secondprocesses step the carrier head rotational speed greater than a platenrotational speed by a ratio of carrier head rotational speed to platenrotational speed of greater than about 1:1, such as a ratio of carrierhead rotational speed to platen rotational speed between about 1.5:1 andabout 12:1, for example between about 1.5:1 and about 3:1, to removematerial from the substrate surface. The respective rotational rates ofthe platen and carrier head are believed to provide reduce shear forcesand frictional forces when contacting the polishing article andsubstrate.

The bias applied for the second electrochemical mechanical polishingstep, or residual polishing step, includes a power application is acurrent density of between about 3 W/cm² and about 20 W/cm². A voltageof between about 1.5 volts and about 3 volts, such as 2 volts, may beused as the applied bias in the second electrochemical processing step.The second bias may be less than the bias of the first electrochemicalpolishing step, the bulk polishing step. The substrate is typicallyexposed to the polishing composition and power application for a periodof time sufficient to remove at least a portion or all of the desiredmaterial disposed thereon. The process may also be performed at atemperature between about 20° C. and about 60° C.

The polymeric inhibitor of the second polishing composition is believedto form a second passivation layer 890 on the surface of the exposedcopper material as shown in FIG. 8B. The second passivation layer 890 isbelieved to chemically and/or electrically insulate material disposed ona substrate surface. The second passivation layer 890 is formed by aphysical and chemical interaction between the second polishingcomposition having the polymeric material and the exposed coppermaterial. The second passivation layer 890 may mechanically interactwith the exposed conductive material by forming a viscous layer thatinhibits fluid flow, or mass transportation, of polishing composition toand from the exposed conductive material. This inhibiting flow can beeffective in reducing removal of copper material in recessed areas. Thesecond passivation layer 890 provides a reduce removal rate when formedover portions of the copper material, and allows a higher removal rateat areas of the substrate surface where the second passivation layer 890is not formed, such as when removed by physical contact with thepolishing pad 620 (or 222).

Mechanical abrasion by a conductive polishing article removes ordisturbs the second passivation layer 890 that insulates or suppressesthe current for anodic dissolution, such that areas of high overburdenare preferentially removed over areas of minimal overburden as thesecond passivation layer 890 is retained in areas of minimal or nocontact with the conductive pad assembly 222. The removal rate of theconductive material 860 covered by the second passivation layer 890 isless than the removal rate of conductive material without the secondpassivation layer 890. As such, the excess material disposed over narrowfeature definitions 820 and the substrate field 850 is removed at ahigher rate than over wide feature definitions 830 still covered by thesecond passivation layer 890.

The thickness and density of the second passivation layer 890 candictate the extent of chemical reactions and/or amount of anodicdissolution. For example, a thicker or denser second passivation layer890 has been observed to result in less anodic dissolution compared tothinner and less dense passivation layers. Thus, control of thecomposition of pH of the composition, i.e., polymeric inhibitors andadditional compounds, allow control of the removal rate and amount ofmaterial removed from the substrate surface.

Referring to FIG. 8C, most, if not all of the conductive layer 860 isremoved to expose barrier layer 840 and conductive trenches 865 bypolishing the substrate with a second, residual, electrochemicalmechanical polishing process including the second electrochemicalmechanical polishing composition described herein. The conductivetrenches 865 are formed by the remaining conductive material 860. Thebarrier material may then be polished by a third polishing step toprovide a planarized substrate surface containing conductive trenches875, as depicted in FIG. 8D. The third polishing process may be a thirdelectrochemical mechanical polishing process or a CMP process. Anexample of a barrier polishing process is disclosed in U.S. patent Ser.No. 10/193,810, entitled, “Dual Reduced Agents for Barrier Removal inChemical Mechanical Polishing,” filed Jul. 11, 2002, published as U.S.patent Publication Number 20030013306, which is incorporated herein tothe extent not inconsistent with the claims aspects and disclosureherein. A further example of a barrier polishing process is disclosed inU.S. patent application Ser. No. 60/572,183 filed on May 17, 2004, whichis incorporated herein to the extent not inconsistent with the claimsaspects and disclosure herein.

After conductive material and barrier material removal processing steps,the substrate may then be buffed to minimize surface defects. Buffingmay be performed with a soft polishing article, i.e., a hardness ofabout 40 or less on the Shore D hardness scale as described and measuredby the American Society for Testing and Materials (ASTM), headquarteredin Philadelphia, Pa., at reduced polishing pressures, such as about 2psi or less.

Optionally, a cleaning solution may be applied to the substrate aftereach of the polishing processes to remove particulate matter and spentreagents from the polishing process as well as help minimize metalresidue deposition on the polishing articles and defects formed on asubstrate surface. An example of a suitable cleaning solution is ElectraClean™, commercially available from Applied Materials, Inc., of SantaClara, Calif.

Finally, the substrate may be exposed to a post polishing cleaningprocess to reduce defects formed during polishing or substrate handling.Such processes can minimize undesired oxidation or other defects incopper features formed on a substrate surface. An example of such a postpolishing cleaning is the application of Electra Clean™, commerciallyavailable from Applied Materials, Inc., of Santa Clara, Calif.

It has been observed that substrate planarized by the processesdescribed herein have exhibited reduced topographical defects, such asdishing and erosion, reduced residues, improved planarity, and improvedsubstrate finish.

Polishing Compositions

Suitable polishing compositions that may be used with the processesdescribed herein are as follows. A bulk polishing composition mayinclude an acid based electrolyte, a chelating agent, an oxidizer, acorrosion inhibitor, an inorganic or organic acid salt, abrasiveparticles, a pH adjusting agent, a pH between about 3 and about 10, anda solvent. A residual polishing composition may include an acid basedelectrolyte, a chelating agent, a corrosion inhibitor, a passivatingpolymeric material, a pH adjusting agent, a pH between about 3 and about10, and a solvent. The residual polishing composition may also includean oxidizer and/or abrasive particulates.

Although the polishing compositions are particularly useful for removingcopper, it is believed that the polishing compositions also may be usedfor the removal of other conductive materials, such as aluminum,platinum, tungsten, titanium, titanium nitride, tantalum, tantalumnitride, cobalt, gold, silver, ruthenium and combinations thereof.

A bulk polishing composition, a first electrochemical mechanicalpolishing step composition, may include an acid based electrolyte, achelating agent, an oxidizer, a corrosion inhibitor, an inorganic ororganic acid salt, abrasive particles, a pH adjusting agent, a pHbetween about 3 and about 10, and a solvent.

The bulk polishing composition includes an acid based electrolyte systemfor providing electrical conductivity. Suitable acid based electrolytesystems include, for example, phosphoric acid based electrolytes,sulfuric acid, nitric acid, perchloric acid, acetic acid, citric acid,salts thereof and combinations thereof. Suitable acid based electrolytesystems include an acid electrolyte, such as phosphoric acid, boric acidand/or citric acid, as well as acid electrolyte derivatives, includingammonium, potassium, sodium, calcium and copper salts thereof. The acidbased electrolyte system may also buffer the composition to maintain adesired pH level for processing a substrate.

Examples of suitable acid based electrolytes include compounds having aphosphate group (Po₄₃ ⁻¹), such as, phosphoric acid, copper phosphate,potassium phosphates (KXH(3−X)PO4) (x=1, 2 or 3), such as potassiumdihydrogen phosphate (KH2PO4), dipotassium hydrogen phosphate (K2HPO4),ammonium phosphates ((NH4)XH(3−X)PO4) (x=1, 2 or 3), such as ammoniumdihydrogen phosphate ((NH4)H2PO4), diammonium hydrogen phosphate((NH4)2HPO4), compounds having a nitrite group (NO31-), such as, nitricacid or copper nitrate, compounds having a boric group (BO33-), such as,orthoboric acid (H3BO3) and compounds having a sulfate group (SO42-),such as sulfuric acid (H2SO4), ammonium hydrogen sulfate ((NH4)HSO4),ammonium sulfate, potassium sulfate, copper sulfate, derivatives thereofand combinations thereof. The invention also contemplates thatconventional electrolytes known and unknown may also be used in formingthe composition described herein using the processes described herein.

The acid based electrolyte system may contains an acidic component thatcan take up about 1 and about 30 percent by weight (wt %) or volume (vol%) of the total composition of solution to provide sufficientconductivity as described herein for practicing the processes describedherein. Examples of acidic components include dihydrogen phosphateand/or diammonium hydrogen phosphate and may be present in the bulkpolishing composition in amounts between about 15 wt % and about 25 wt%. Alternately, phosphoric acid may be present in concentrations up to30 wt %, for example, between about 2 wt % and about 6 wt %. The acidbased electrolyte may also be added in solution, for example, the 6 wt.% of phosphoric acid may be from 85% aqueous phosphoric acid solutionfor an actual phosphoric acid composition of about 5.1 wt. %.

One aspect or component of the present invention is the use of one ormore chelating agents to complex with the surface of the substrate toenhance the electrochemical dissolution process. In any of theembodiments described herein, the chelating agents can bind to aconductive material, such as copper ions, increase the removal rate ofmetal materials and/or improve dissolution uniformity across thesubstrate surface. The metal materials for removal, such as copper, maybe in any oxidation state, such as 0, 1, or 2, before, during or afterligating with a functional group. The functional groups can bind themetal materials created on the substrate surface during processing andremove the metal materials from the substrate surface. The chelatingagents may also be used to buffer the bulk polishing composition tomaintain a desired pH level for processing a substrate. The chelatingagents may also form or enhance the formation of the second passivationlayer on the substrate surface.

The one or more chelating agents can include compounds having one ormore functional groups selected from the group of amine groups, amidegroups, carboxylate groups, dicarboxylate groups, tricarboxylate groups,hydroxyl groups, a mixture of hydroxyl and carboxylate groups, andcombinations thereof. The one or more chelating agents may also includesalts of the chelating agents described herein. The bulk polishingcomposition may include one or more chelating agents at a concentrationbetween about 0.1% and about 15% by volume or weight, but preferablyutilized between about 0.1% and about 4% by volume or weight. Forexample, about 2% by volume of ethylenediamine may be used as achelating agent.

Examples of suitable chelating agents having one or more carboxylategroups include citric acid, tartaric acid, succinic acid, oxalic acid,amino acids, salts thereof, and combinations thereof. For example,chelating agents may include ammonium citrate, potassium citrate,ammonium succinate, potassium succinate, ammonium oxalate, potassiumoxalate, potassium tartrate, and combinations thereof. The salts mayhave multi-basic states, for example, citrates have mono-, di- andtri-basic states. Other suitable acids having one or more carboxylategroups include acetic acid, adipic acid, butyric acid, capric acid,caproic acid, caprylic acid, glutaric acid, glycolic acid, formaic acid,fumaric acid, lactic acid, lauric acid, malic acid, maleic acid, malonicacid, myristic acid, plamitic acid, phthalic acid, propionic acid,pyruvic acid, stearic acid, valeric acid, derivatives thereof, saltsthereof and combinations thereof. Further examples of suitable chelatingagents include compounds having one or more amine and amide functionalgroups, such as ethylenediamine (EDA), diethylenetriamine,diethylenetriamine derivatives, hexadiamine, amino acids, glycine,ethylenediaminetetraacetic acid (EDTA), methylformamide, derivativesthereof, salts thereof and combinations thereof. For example, EDTAincludes the acid as well as a variety of salts, such as sodium,potassium and calcium (e.g., Na₂EDTA, Na₄EDTA, K₄EDTA or Ca₂EDTA).

In any of the embodiments described herein, the inorganic or organicacid salts may be used to perform as a chelating agent. The bulkpolishing composition may include one or more inorganic or organic saltsat a concentration between about 0.1% and about 15% by volume or weightof the composition, for example, between about 0.1% and about 8% byvolume or weight. For example, about 2% by weight of ammonium citratemay be used in the bulk polishing composition. The chelating agent mayalso be added in solution or in a substantially pure form, for example,ammonium citrate may be added in a 98% pure form.

Examples of suitable inorganic or organic acid salts include ammoniumand potassium salts or organic acids, such as ammonium oxalate, ammoniumcitrate, ammonium succinate, monobasic potassium citrate, dibasicpotassium citrate, tribasic potassium citrate, potassium tartarate,ammonium tartarate, potassium succinate, potassium oxalate, andcombinations thereof. Additionally, ammonium and potassium salts of thecarboxylate acids may also be used.

In any of the embodiments described herein, the corrosion inhibitors canbe added to reduce the oxidation or corrosion of metal surfaces byenhancing the formation of the second passivation layer 890 thatminimizes the chemical interaction between the substrate surface and thesurrounding electrolyte. The layer of material formed by the corrosioninhibitors thus tends to suppress or minimize the electrochemicalcurrent from the substrate surface to limit electrochemical depositionand/or dissolution. The bulk polishing composition may include betweenabout 0.001% and about 5.0% by weight of the organic compound from oneor more azole groups. The commonly preferred range being between about0.2% and about 0.4% by weight. The corrosion inhibitor may also be addedin solution or in a substantially pure form, for example, benzotriazolemay be added in a 99% pure form.

Suitable corrosion inhibitors include compounds having a nitrogen atom(N), such as organic compounds having azole groups. Examples of suitablecompounds include benzotriazole (BTA), mercaptobenzotriazole,5-methyl-1-benzotriazole (TTA), and combinations thereof. Other suitablecorrosion inhibitors include film forming agents that are cycliccompounds, for example, imidazole, benzimidazole, triazole, andcombinations thereof. Derivatives of benzotriazole, imidazole,benzimidazole, triazole, with hydroxy, amino, imino, carboxy, mercapto,nitro and alkyl substituted groups may also be used as corrosioninhibitors. Other corrosion inhibitor includes urea and thiourea amongothers.

Alternatively, polymeric inhibitors, for non-limiting examples,polyalkylaryl ether phosphate or ammonium nonylphenol ethoxylatesulfate, may be used in replacement or conjunction with azole containingcorrosion inhibitors in an amount between about 0.002% and about 1.0% byvolume or weight of the composition.

One or more pH adjusting agents is preferably added to the bulkpolishing composition to achieve a pH between about 2 and about 10, andpreferably between a pH of about 3 and about 7. The amount of pHadjusting agent can vary as the concentration of the other components isvaried in different formulations, but in general the total solution mayinclude up and about 70 wt % of the one or more pH adjusting agents, butpreferably between about 0.2% and about 25% by volume. Differentcompounds may provide different pH levels for a given concentration, forexample, the composition may include between about 0.1% and about 10% byvolume of a base, such as potassium hydroxide, ammonium hydroxide,sodium hydroxide or combinations thereof, providing the desired pHlevel. The pH adjusting eagent may also be added in solution or in asubstantially pure form, for example, potassium hydroxide may be addedin a 45% aqueous potassium hydroxide solution.

The one or more pH adjusting agents can be chosen from a class oforganic acids, for example, carboxylic acids, such as acetic acid,citric acid, oxalic acid, phosphate-containing components includingphosphoric acid, ammonium phosphates, potassium phosphates, andcombinations thereof, or a combination thereof. Inorganic acidsincluding phosphoric acid, sulfuric acid, hydrochloric, nitric acid,derivatives thereof and combinations thereof, may also be used as a pHadjusting agent in the bulk polishing composition.

The balance or remainder of the bulk polishing compositions describedherein is a solvent, such as a polar solvent, including water,preferably deionized water. Other solvents may be used solely or incombination with water, such as organic solvents. Organic solventsinclude alcohols, such as isopropyl alcohol or glycols, ethers, such asdiethyl ether, furans, such as tetrahydrofuran, hydrocarbons, such aspentane or heptane, aromatic hydrocarbons, such as benzene or toluene,halogenated solvents, such as methylene chloride or carbontetrachloride, derivatives, thereof and combinations thereof.

The bulk polishing composition may further include one or more surfacefinish enhancing and/or removal rate enhancing materials includingabrasive particles, one or more oxidizers, and combinations thereof.

Abrasive particles may be used to improve the surface finish and removalrate of conductive materials from the substrate surface duringpolishing. The addition of abrasive particles to the bulk polishingcomposition can allow the final polished surface to achieve a surfaceroughness of that comparable with a conventional CMP process even at lowpad pressures. Surface finish, or surface roughness, has been shown tohave an effect on device yield and post polishing surface defects.Abrasive particles may comprise up and about 30 wt % of the bulkpolishing composition during processing. A concentration between about0.001 wt % and about 5 wt % of abrasive particles may be used in thebulk polishing composition.

Suitable abrasives particles include inorganic abrasives, polymericabrasives, and combinations thereof. Inorganic abrasive particles thatmay be used in the electrolyte include, but are not limited to, silica,alumina, zirconium oxide, titanium oxide, cerium oxide, germania, or anyother abrasives of metal oxides, known or unknown. For example,colloidal silica may be positively activated, such as with an aluminamodification or a silica/alumina composite. The typical abrasiveparticle size used in one embodiment of the current invention isgenerally between about 1 nm and about 1,000 nm, preferably betweenabout 10 nm and about 100 nm. Generally, suitable inorganic abrasiveshave a Mohs hardness of greater than 6, although the inventioncontemplates the use of abrasives having a lower Mohs hardness value.

The polymer abrasives described herein may also be referred to as“organic polymer particle abrasives”, “organic abrasives” or “organicparticles.” The polymeric abrasives may comprise abrasive polymericmaterials. Examples of polymeric abrasives materials includepolymethylmethacrylate, polymethyl acrylate, polystyrene,polymethacrylonitrile, and combinations thereof.

The polymeric abrasives may have a Hardness Shore D of between about 60and about 80, but can be modified to have greater or lesser hardnessvalue. The softer polymeric abrasive particles can help reduce frictionbetween a polishing article and substrate and may result in a reductionin the number and the severity of scratches and other surface defects ascompared to inorganic particles. A harder polymeric abrasive particlemay provide improved polishing performance, removal rate and surfacefinish as compared to softer materials.

The hardness of the polymer abrasives can be varied by controlling theextent of polymeric cross-linking in the abrasives, for example, ahigher degree of cross-linking produces a greater hardness of polymerand, thus, abrasive. The polymeric abrasives are typically formed asspherical shaped beads having an average diameter between about 0.1micron and about 20 microns or less.

The polymeric abrasives may be modified to have one ore more functionalgroups that can bind to the conductive material or conductive materialions, thereby facilitating the electrochemical mechanical polishingremoval of material from the surface of a substrate. For example, ifcopper is to be removed in the polishing process, the organic polymerparticles can be modified to have an amine group, a carboxylate group, apyridine group, a hydroxide group, ligands with a high affinity forcopper, or combinations thereof, to bind the removed copper assubstitutes for or in addition to the chemically active agents in thebulk polishing composition, such as the chelating agents or corrosioninhibitors. The substrate surface material, such as copper, may be inany oxidation state, such as 0, 1+, or 2+, before, during or afterligating with a functional group. The functional groups can bind to themetal material(s) on the substrate surface to help improve theuniformity and surface finish of the substrate surface.

Additionally, the polymeric abrasives have desirable chemicalproperties, for example, the polymer abrasives are stable over a broadpH range and are not prone to aggregating to each other, which allow thepolymeric abrasives to be used with reduced or no surfactant or nodispersing agent in the composition.

Alternatively, inorganic particles coated with the polymeric materialsdescribed herein may also be used with the bulk polishing composition.It is within the scope of the current invention for the bulk polishingcomposition to contain polymeric abrasives, inorganic abrasives, thepolymeric coated inorganic abrasives, and any combination thereofdepending on the desired polishing performance and results.

The optional oxidizer can be present in the bulk polishing compositionin an amount ranging between about 0.01% and about 100% by volume orweight, for example, between about 0.1% and about 20% by volume orweight. In an embodiment of the bulk polishing composition, betweenabout 0.1% and about 15% by volume or weight of hydrogen peroxide ispresent in the bulk polishing composition. In one embodiment, theoxidizer is added to the rest of the bulk polishing composition justprior to beginning the electrochemical mechanical polishing process. Theoxidizer may be added to the composition in a solution, such as a 30%aqueous hydrogen peroxide solution or a 40% aqueous hydrogen peroxidesolution.

Examples of suitable oxidizers include peroxy compounds, e.g., compoundsthat may disassociate through hydroxy radicals, such as hydrogenperoxide and its adducts including urea hydrogen peroxide,percarbonates, and organic peroxides including, for example, alkylperoxides, cyclical or aryl peroxides, benzoyl peroxide, peracetic acid,and ditertbutyl peroxide. Sulfates and sulfate derivatives, such asmonopersulfates and dipersulfates may also be used including forexample, ammonium peroxydisulfate, potassium peroxydisulfate, ammoniumpersulfate, and potassium persulfate. Salts of peroxy compounds, such assodium percarbonate and sodium peroxide may also be used.

The oxidizer can also be an inorganic compound or a compound containingan element in its highest oxidation state. Examples of inorganiccompounds and compounds containing an element in its highest oxidationstate include but are not limited to periodic acid, periodate salts,perbromic acid, perbromate salts, perchloric acid, perchloric salts,perbonic acid, nitrate salts (such as cerium nitrate, iron nitrate,ammonium nitrate), ferrates, perborate salts and permanganates. Otheroxidizers include bromates, chlorates, chromates, iodates, iodic acid,and cerium (IV) compounds such as ammonium cerium nitrate.

One or more oxidizers may be used herein to enhance the removal orremoval rate of the conductive material from the substrate surface. Anoxidizer is generally an agent that reacts with a material by acceptingan electron(s). In the current embodiment the oxidizer is used to reactwith the surface of the substrate that is to be polished, which thenaids in the removal of the desired material. For example, an oxidizermay be used to oxidize a metal layer to a corresponding oxide orhydroxide, for example, copper to copper oxide. Existing copper that hasbeen oxidized, including Cu¹⁺ ions, may further be oxidized to a higheroxidation state, such as Cu²⁺ ions, which may then promote the reactionwith one or more of the chelating agents. Also, in some instances theoxidizer can be used in some chemistries (e.g., low pH) that can enhancethe chemical etching of the surface of the substrate to further increasethe removal rate from the anode surface. In cases where no bias isapplied to the surface of the substrate the inhibitors and chelatingagents will complex with the metal ions on the surface that becomedislodged from the surface due to the relative motion and pressureapplied by the conductive article 203. The addition of abrasives canfurther improve the removal rate of the complexed metal ions due to theabrasive particles ability to increase that contact area between theconductive article 203 and the substrate surface.

In the case of electrochemical mechanical polishing, the conductivelayer on the substrate surface is biased anodically above a thresholdpotential, by use of the power source 242 and the electrode 209, thuscausing the metal on the substrate surface to “oxidize” (i.e., a metalatom gives up one or more electrons to the power source 242). Theionized or “oxidized” metal atoms thus dissolve into the electrolytesolution with the help of components in the electrolyte. In the casewhere copper is the desired material to be removed, it can be oxidizedto a Cu¹⁺ or a Cu²⁺ oxidation state. Due to the presence of theinhibitors and/or chelating agents found in the bulk polishingcomposition, the electrochemical dissolution process of the metal ionsinto the electrolyte is more limited than a polishing composition whichdoes not contain these components. The presence of the inhibitors and/orchelating agents also appears to have an effect on the attachmentstrength of the metal ion(s) and inhibitor and/or chelating agentcomplex to the surface of the substrate. It has been found that in oneembodiment that the removal rate in an electrochemical mechanicalpolishing process can be increased by the addition of an oxidizer. It isthought that the oxidizer tends to further oxidize the metal ions formeddue to the anodic bias, which in the case of copper brings it to themore stable Cu²⁺ oxidation state. The inhibitors and/or chelating agentsfound in the bulk polishing composition complex with the oxidized metalions which tend to have a lower attachment, or bond, strength due to theway the inhibitor bonds to the oxidized metal ion and metal surface. Thelower attachment strength allows the complexed metal ion to be moreeasily and efficiently removed due to the interaction of the substratesurface and the conductive article 203. The addition of abrasives to theelectrochemical mechanical polishing bulk polishing composition canfurther improve the removal rate of the complexed metal ions due to theabrasive particles ability to increase contact area between theconductive article 203 and the substrate surface.

Further, controlling the amounts and types of constituents of the bulkpolishing composition, such as corrosion inhibitors and oxidizers, canresult in tuning the desired removal rate of the process. For examplereduced amounts of corrosion inhibitor will result in an increase in thematerial removal rate as compared to compositions having highercorrosion inhibitor concentrations. In cases where the bulk polishingcomposition does not contain corrosion inhibitors the electrochemicalmechanical polishing material removal rate is greatly increased over apolishing composition which contains a corrosion inhibitor due to theformation of the metal ions and inhibitor complex which tends to shieldthe surface of the substrate to the electrolyte. Likewise reducedamounts of oxidizers will generally result in lower removal ratescompared to compositions having higher oxidizer compositions. It hasbeen suggested that at low concentrations of the oxidizer, the corrosioninhibitor and/or chelating agent can complex with a metal ion before itbecomes oxidized further by the oxidizer due to kinetic effects limitingthe supply of the oxidizer to the surface of the substrate. Thecorrosion inhibitor and metal ion complex can thus affect the removalefficiency due to the formation of the stronger attachment strengthcomplexed metal ions.

An example of a bulk polishing composition described herein includesabout 2% by volume ethylenediamine, about 2% by weight ammonium citrate,about 0.3% by weight benzotriazole, between about 0.1% and about 3% byvolume or weight, for example, about 0.45% hydrogen peroxide, and/orabout between about 0.01% and 1% by weight, for example 0.15% by weight,of abrasive particles, and about 6% by volume phosphoric acid. The pH ofthe composition is about 5, which may be achieved by, for example, thecomposition further including potassium hydroxide to adjust the pH tothe preferred range. The remainder of the bulk polishing composition isdeionized water.

The bulk polishing composition may include one or more additivecompounds. Additive compounds include electrolyte additives including,but not limited to, suppressors, enhancers, levelers, brighteners,stabilizers, and stripping agents to improve the effectiveness of thebulk polishing composition in polishing of the substrate surface. Forexample, certain additives may decrease the ionization rate of the metalatoms, thereby inhibiting the dissolution process, whereas otheradditives may provide a finished, shiny substrate surface. The additivesmay be present in the bulk polishing composition in concentrations upand about 15% by weight or volume, and may vary based upon the desiredresult after polishing.

Further examples of additives to the bulk polishing composition are morefully described in U.S. patent application Ser. No. 10/141,450, filed onMay 7, 2002, which is incorporated by reference herein to the extent notinconsistent with the claimed aspects and disclosure herein.

A residual polishing composition may include an acid based electrolyte,a chelating agent, a corrosion inhibitor, a passivating polymericmaterial, a pH adjusting agent, a pH between about 3 and about 10, and asolvent. The residual polishing composition may be an abrasive freepolishing composition and optionally, may further include an oxidizer,abrasive particles, or a combination of the two.

The residual polishing composition includes an acid based electrolytesystem for providing electrical conductivity. Suitable acid basedelectrolyte systems include, for example, phosphoric acid basedelectrolytes, sulfuric acid, nitric acid, perchloric acid, acetic acid,citric acid, salts thereof and combinations thereof. Suitable acid basedelectrolyte systems include an acid electrolyte, such as phosphoricacid, boric acid and/or citric acid, as well as acid electrolytederivatives, including ammonium, potassium, sodium, calcium and coppersalts thereof. The acid based electrolyte system may also buffer thecomposition to maintain a desired pH level for processing a substrate.

Examples of suitable acid based electrolytes include compounds having aphosphate group (PO4³⁻), such as, phosphoric acid, copper phosphate,potassium phosphates (K_(X)H(_(3−x))PO₄) (x=1, 2 or 3), such aspotassium dihydrogen phosphate (KH₂PO₄), dipotassium hydrogen phosphate(K2HPO4), ammonium phosphates ((NH₄)XH(3−X)PO₄) (x=1, 2 or 3), such asammonium dihydrogen phosphate ((NH₄)H₂PO₄), diammonium hydrogenphosphate ((NH₄)₂HPO₄), compounds having a nitrite group (NO₃ ¹⁻), suchas, nitric acid or copper nitrate, compounds having a boric group (BO₃³⁻), such as, orthoboric acid (H₃BO₃) and compounds having a sulfategroup (SO₄ ²⁻), such as sulfuric acid (H₂SO₄), ammonium hydrogen sulfate((NH₄)HSO₄), ammonium sulfate, potassium sulfate, copper sulfate,derivatives thereof and combinations thereof. The invention alsocontemplates that conventional electrolytes known and unknown may alsobe used in forming the composition described herein using the processesdescribed herein.

The acid based electrolyte system may contains an acidic component thatcan take up about 1 and about 30 percent by weight (wt %) or volume (vol%) of the total composition of solution to provide suitable conductivityfor practicing the processes described herein. Examples of acidiccomponents include dihydrogen phosphate and/or diammonium hydrogenphosphate and may be present in the polishing composition in amountsbetween about 15 wt % and about 25 wt %. Alternately, phosphoric acidmay be present in concentrations up to 30 wt %, for example, betweenabout 2 wt % and about 6 wt %. The acid based electrolyte may also beadded in solution, for example, the 6 wt. % of phosphoric acid may befrom 85% aqueous phosphoric acid solution for an actual phosphoric acidcomposition of about 5.1 wt. %.

One aspect or component of the present invention is the use of one ormore chelating agents to complex with metal ions and/or the surface ofthe substrate to enhance the electrochemical dissolution process. Thechelating agents may also be used to buffer the polishing composition tomaintain a desired pH level for processing a substrate. The chelatingagents may also enhance the formation of the second passivation layer890 on the substrate surface.

In any of the embodiments described herein, the inorganic or organicacid salts may be used to perform as a chelating agent. The polishingcomposition may include one or more inorganic or organic salts at aconcentration between about 0.1% and about 15% by volume or weight ofthe composition, for example, between about 0.1% and about 8% by volumeor weight. For example, about 2% by weight of ammonium citrate may beused in the polishing composition. The chelating agent may also be addedin solution or in a substantially pure form, for example, ammoniumcitrate may be added in a 98% pure form.

Examples of suitable inorganic or organic acid salts include ammoniumand potassium salts or organic acids, such as ammonium oxalate, ammoniumcitrate, ammonium succinate, monobasic potassium citrate, dibasicpotassium citrate, tribasic potassium citrate, potassium tartarate,ammonium tartarate, potassium succinate, potassium oxalate, andcombinations thereof. Additionally, ammonium and potassium salts of thecarboxylate acids may also be used.

Alternatively, and additionally, one or more chelating agents caninclude compounds having one or more functional groups selected from thegroup of amine groups, amide groups, carboxylate groups, dicarboxylategroups, tricarboxylate groups, hydroxyl groups, a mixture of hydroxyland carboxylate groups, and combinations thereof. The polishingcomposition may include one or more chelating agents at a concentrationbetween about 0.1% and about 15% by volume or weight, but preferablyutilized between about 0.1% and about 4% by volume or weight. Forexample, about 2% by volume of ethylenediamine may be used as achelating agent.

Examples of suitable chelating agents having one or more carboxylategroups include citric acid, tartaric acid, succinic acid, oxalic acid,amino acids, salts thereof, and combinations thereof. For example,chelating agents may include ammonium citrate, potassium citrate,ammonium succinate, potassium succinate, ammonium oxalate, potassiumoxalate, potassium tartrate, and combinations thereof. The salts mayhave multi-basic states, for example, citrates have mono-, di- andtri-basic states. Other suitable acids having one or more carboxylategroups include acetic acid, adipic acid, butyric acid, capric acid,caproic acid, caprylic acid, glutaric acid, glycolic acid, formaic acid,fumaric acid, lactic acid, lauric acid, malic acid, maleic acid, malonicacid, myristic acid, plamitic acid, phthalic acid, propionic acid,pyruvic acid, stearic acid, valeric acid, derivatives thereof, saltsthereof and combinations thereof. Further examples of suitable chelatingagents include compounds having one or more amine and amide functionalgroups, such as ethylenediamine (EDA), diethylenetriamine,diethylenetriamine derivatives, hexadiamine, amino acids, glycine,ethylenediaminetetraacetic acid (EDTA), methylformamide, derivativesthereof, salts thereof and combinations thereof. For example, EDTAincludes the acid as well as a variety of salts, such as sodium,potassium and calcium (e.g., Na₂EDTA, Na₄EDTA, K₄EDTA or Ca₂EDTA).

In any of the embodiments described herein, the corrosion inhibitors canbe added to reduce the oxidation or corrosion of metal surfaces byenhancing the forming of the passivation layers that minimizes thechemical interaction between the substrate surface and the surroundingelectrolyte. The layer of material formed by the corrosion inhibitorsthus tends to suppress or minimize the electrochemical current from thesubstrate surface to limit electrochemical deposition and/ordissolution. The polishing composition may include between about 0.001%and about 5.0% by weight of the organic compound from one or more azolegroups. The commonly preferred range being between about 0.2% and about0.4% by weight. The corrosion inhibitor may also be added in solution orin a substantially pure form, for example, benzotriazole may be added ina 99% pure form.

Suitable corrosion inhibitors include compounds having a nitrogen atom(N), such as organic compounds having azole groups. Examples of organiccompounds having azole groups include benzotriazole (BTA),mercaptobenzotriazole, 5-methyl-1-benzotriazole (TTA), and combinationsthereof. Other suitable corrosion inhibitors include film forming agentsthat are cyclic compounds, for example, imidazole, benzimidazole,triazole, and combinations thereof. Derivatives of benzotriazole,imidazole, benzimidazole, triazole, with hydroxy, amino, imino, carboxy,mercapto, nitro and alkyl substituted groups may also be used ascorrosion inhibitors. Other corrosion inhibitor includes urea andthiourea among others.

The residue composition includes polymeric inhibitors, which by chemicalor physical means, form a layer of material which minimizes the chemicalinteraction between the substrate surface and the surroundingelectrolyte. The layer of material formed by the inhibitors may suppressor minimize the electrochemical current from the substrate surface tolimit electrochemical deposition and/or dissolution. By a physicalmechanism, the second passivation layer 885 may be of a viscous formthat inhibits fluid flow to and from the conductive material, limitingthe removal rate of material therefrom.

Suitable polymeric inhibitors include compounds having a nitrogen atom(N), an oxygen atom (O), or a combination of the two. Polymericinhibitors include ethylene imine based polymeric materials, such aspolyethylene imine (PEI) having a molecular weight between about 400 andabout 1000000 comprising (—CH₂—CH₂—NH—) monomer units, ethylene glycolbased polymeric materials, such as polyethylene glycol (PEG) having amolecular weight between about 200 and about 100000 comprising(OCH₂CH₂)_(N) monomer units. Polyamine and polyimide polymeric materialmay also be used as polymeric inhibitors in the composition. Othersuitable polymeric inhibitors include oxide polymers, such as,polypropylene oxide and ethylene oxide propylene/oxide co-polymer(EOPO), with a Molecular Weight range between about 200 and about100000. An example of a suitable polymeric inhibitor includes XP-1296,containing polyamine polymer, commercially available from Rohm and HassElectronic Materials of Marlborough, Mass., and Compound S-900,commercially available from Enthone-OMI Inc. of New Haven, Conn.

The polymeric inhibitor may be present in the composition of thisinvention in amounts ranging between about 0.001 wt. % and about 2 wt.%, such as between about 0.005 wt. % and about 1 wt. %, for example,between about 0.01 wt. % and about 0.5 vol %. A polymeric inhibitor of2000 or 750000 molecular weight polyethylenimine in a concentration ofabout 0.025 wt. % may be used in the composition. More than onepolymeric inhibitor may be included in the residual polishingcomposition. Some polymeric inhibitor may be added the composition in asolution, for example, the residual polishing composition may include0.5 wt. % PEI with a 2000 molecular weight of a 5% aqueous PEI solutionand/or 0.5 wt. % XP with a 2000 molecular weight of a 10% aqueous XPsolution.

One or more pH adjusting agents is preferably added to the polishingcomposition to achieve a pH between about 2 and about 10, and preferablyan acidic pH between about 3 and less than about 7. The amount of pHadjusting agent can vary as the concentration of the other components isvaried in different formulations, but in general the total solution mayinclude up and about 70 wt % of the one or more pH adjusting agents, butpreferably between about 0.2% and about 25% by volume. Differentcompounds may provide different pH levels for a given concentration, forexample, the composition may include between about 0.1% and about 10% byvolume of a base, such as potassium hydroxide, ammonium hydroxide,sodium hydroxide or combinations thereof, providing the desired pHlevel. The one or more pH adjusting agents may be added the compositionin a solution, for example, the residual polishing composition mayinclude potassium hydroxide (KOH) of a 40% or 45% water solution.

The one or more pH adjusting agents can be chosen from a class oforganic acids, for example, carboxylic acids, such as acetic acid,citric acid, oxalic acid, phosphate-containing components includingphosphoric acid, ammonium phosphates, potassium phosphates, andcombinations thereof, or a combination thereof. Inorganic acidsincluding phosphoric acid, sulfuric acid, hydrochloric, nitric acid,derivatives thereof and combinations thereof, may also be used as a pHadjusting agent in the polishing composition.

The balance or remainder of the polishing compositions described hereinis a solvent, such as a polar solvent, including water, preferablydeionized water. Other solvent may be used solely or in combination withwater, such as organic solvents. Organic solvents include alcohols, suchas isopropyl alcohol or glycols, ethers, such as diethyl ether, furans,such as tetrahydrofuran, hydrocarbons, such as pentane or heptane,aromatic hydrocarbons, such as benzene or toluene, halogenated solvents,such as methylene chloride or carbon tetrachloride, derivatives, thereofand combinations thereof.

While not being limited to any particular theory, it is believed that alone pair of electrons in the polymer's functional groups which includenitrogen (n) atom or oxygen (O) atom interact with the copper materialon the surface to form a passivation layer. A corrosion inhibitor havinga nitrogen atom may also contribute to forming the passivation layerwith the polymeric passivation material. Chelating agents that have adonor electron or a lone pair of electrons may also contribute to theformation of the passivation layer in a similar manner. The passivationlayer formed from the second polishing composition may mechanicallyinteract with the exposed conductive material by forming a viscous layerthat inhibits fluid flow, or mass transportation, of polishingcomposition to and from the exposed conductive material. The viscouslayer may be formed from a phosphoric acid or phosphoric acidderivative. This inhibiting flow can be effective in reducing removal ofcopper material in recessed areas.

While the residual polishing compositions may be described as oxidizerfree and/or abrasive free polishing compositions, an alterativeembodiment of the composition may include an oxidizer, abrasiveparticles, or combinations thereof.

Optionally, the residual polishing composition may include one or moreoxidizers. The oxidizer can be present in the polishing composition inan amount ranging between about 0.01% and about 100% by volume orweight, for example, between about 0.1% and about 20% by volume orweight. In an embodiment of the polishing composition, between about0.1% and about 15% by volume or weight of hydrogen peroxide is presentin the polishing composition. The oxidizer may be added to thecomposition in a solution, such as a 30% aqueous hydrogen peroxidesolution or a 40% aqueous hydrogen peroxide solution.

In one embodiment, the oxidizer is added to the rest of the polishingcomposition just prior to beginning the electrochemical mechanicalpolishing process. Examples of suitable oxidizers include peroxycompounds, e.g., compounds that may disassociate through hydroxyradicals, such as hydrogen peroxide and its adducts including ureahydrogen peroxide, percarbonates, and organic peroxides including, forexample, alkyl peroxides, cyclical or aryl peroxides, benzoyl peroxide,peracetic acid, and ditertbutyl peroxide. Sulfates and sulfatederivatives, such as monopersulfates and dipersulfates may also be usedincluding for example, ammonium peroxydisulfate, potassiumperoxydisulfate, ammonium persulfate, and potassium persulfate. Salts ofperoxy compounds, such as sodium percarbonate and sodium peroxide mayalso be used.

The oxidizer can also be an inorganic compound or a compound containingan element in its highest oxidation state. Examples of inorganiccompounds and compounds containing an element in its highest oxidationstate include but are not limited to periodic acid, periodate salts,perbromic acid, perbromate salts, perchloric acid, perchloric salts,perbonic acid, nitrate salts (such as cerium nitrate, iron nitrate,ammonium nitrate), ferrates, perborate salts and permanganates. Otheroxidizers include bromates, chlorates, chromates, iodates, iodic acid,and cerium (IV) compounds such as ammonium cerium nitrate.

Optionally, abrasive particles, referred to as abrasives, may maycomprise up and about 30 wt % of the residual polishing compositionduring processing, such as a concentration between about 0.001 wt % andabout 5 wt % of abrasive particles in the bulk polishing composition.

Suitable abrasives particles include inorganic abrasives, polymericabrasives, and combinations thereof. Inorganic abrasive particles thatmay be used in the electrolyte include, but are not limited to, silica,alumina, zirconium oxide, titanium oxide, cerium oxide, germania, or anyother abrasives of metal oxides, known or unknown. For example,colloidal silica may be positively activated, such as with an aluminamodification or a silica/alumina composite. The typical abrasiveparticle size used in one embodiment of the current invention isgenerally between about 1 nm and about 1,000 nm, preferably betweenabout 10 nm and about 100 nm. Generally, suitable inorganic abrasiveshave a Mohs hardness of greater than 6, although the inventioncontemplates the use of abrasives having a lower Mohs hardness value.

The polymer abrasives described herein may also be referred to as“organic polymer particle abrasives”, “organic abrasives” or “organicparticles.” The polymeric abrasives may comprise abrasive polymericmaterials. Examples of polymeric abrasives materials includepolymethylmethacrylate, polymethyl acrylate, polystyrene,polymethacrylonitrile, and combinations thereof.

The polymeric abrasives may have a Hardness Shore D of between about 60and about 80, but can be modified to have greater or lesser hardnessvalue. The softer polymeric abrasive particles can help reduce frictionbetween a polishing article and substrate and may result in a reductionin the number and the severity of scratches and other surface defects ascompared to inorganic particles. A harder polymeric abrasive particlemay provide improved polishing performance, removal rate and surfacefinish as compared to softer materials. The hardness of the polymerabrasives can be varied by controlling the extent of polymericcross-linking in the abrasives, for example, a higher degree ofcross-linking produces a greater hardness of polymer and, thus,abrasive. The polymeric abrasives are typically formed as sphericalshaped beads having an average diameter between about 0.1 micron andabout 20 microns or less.

The polymeric abrasives may be modified to have functional groups, e.g.,one or more functional groups, that have an affinity for, i.e., can bindto, the conductive material or conductive material ions at the surfaceof the substrate, thereby facilitating the electrochemical mechanicalpolishing removal of material from the surface of a substrate. Forexample, if copper is to be removed in the polishing process, theorganic polymer particles can be modified to have an amine group, acarboxylate group, a pyridine group, a hydroxide group, ligands with ahigh affinity for copper, or combinations thereof, to bind the removedcopper as substitutes for or in addition to the chemically active agentsin the bulk polishing composition, such as the chelating agents orcorrosion inhibitors. The substrate surface material, such as copper,may be in any oxidation state, such as 0, 1+, or 2+, before, during orafter ligating with a functional group. The functional groups can bindto the metal material(s) on the substrate surface to help improve theuniformity and surface finish of the substrate surface.

Additionally, the polymeric abrasives have desirable chemicalproperties, for example, the polymer abrasives are stable over a broadpH range and are not prone to aggregating to each other, which allow thepolymeric abrasives to be used with reduced or no surfactant or nodispersing agent in the composition.

Alternatively, inorganic particles coated with the polymeric materialsdescribed herein may also be used with the bulk polishing composition.It is within the scope of the current invention for the bulk polishingcomposition to contain polymeric abrasives, inorganic abrasives, thepolymeric coated inorganic abrasives, and any combination thereofdepending on the desired polishing performance and results.

The residual polishing composition may include one or more additivecompounds. Additive compounds include electrolyte additives including,but not limited to, suppressors, enhancers, levelers, brighteners,stabilizers, and stripping agents to improve the effectiveness of theresidual polishing composition in polishing of the substrate surface.For example, certain additives may decrease the ionization rate of themetal atoms, thereby inhibiting the dissolution process, whereas otheradditives may provide a finished, shiny substrate surface. The additivesmay be present in the residual polishing composition in concentrationsup and about 15% by weight or volume, and may vary based upon thedesired result after polishing.

Electrochemical mechanical polishing compositions of varyingcompositions may be used to remove bulk material and residual material,such as copper and/or copper alloys, as well as to remove barriermaterials, such as tantalum nitrides or titanium nitrides. Specificformulations of the polishing compositions are used to remove theparticular materials. Polishing compositions utilized during embodimentsherein are advantageous for electrochemical mechanical polishingprocesses. Generally, electrochemical mechanical polishing compositionsare much more conductive than traditional CMP solutions. Theelectrochemical mechanical polishing compositions have a conductivity ofabout 10 mS/cm or higher, while traditional CMP solutions have aconductivity between about 3 mS/cm and about 5 mS/cm. The conductivityof the electrochemical mechanical polishing compositions greatlyinfluences that rate at which the electrochemical mechanical polishingprocess advances, i.e., more conductive solutions have a faster materialremoval rate. For removing bulk material, the electrochemical mechanicalpolishing composition has a conductivity of about 10 mS/cm or higher,for example, between about 10 mS/cm and about 100 mS/cm, preferably in arange between about 30 mS/cm and about 60 mS/cm. For residual material,the electrochemical mechanical polishing composition has a conductivityof about 10 mS/cm or higher, for example, between about 10 mS/cm andabout 100 mS/cm, preferably in a range between about 20 mS/cm and about80 mS/cm.

It has been observed that a substrate processed with the polishingcomposition described herein has improved surface finish, including lesssurface defects, such as dishing, erosion (removal of dielectricmaterial surrounding metal features), and scratches, as well as improvedplanarity.

The following non-limiting examples are provided to further illustrateembodiments of the invention. However, the examples are not intended tobe all-inclusive and are not intended to limit the scope of theinventions described herein.

The compositions described herein may be further disclosed by theexamples as follows.

EXAMPLES

The following non-limiting examples are provided to further illustrateembodiments of the invention. However, the examples are not intended tobe all-inclusive and are not intended to limit the scope of theinventions described herein.

Examples of residual compositions include:

Example 1

about 5.1 vol % of phosphoric acid;

about 2 wt. % of ammonium citrate;

about 0.3 wt. % of benzotriazole;

about 0.5 vol % of XP-1296;

about 0.025 vol % of 750000 molecular weight polyethylene imine (PEI);

deionized water; and

potassium hydroxide to provide a pH of about 5.75.

Example 2

about 5.1 vol % of phosphoric acid;

about 2 wt. % of ammonium citrate;

about 0.3 wt % of benzotriazole;

about 0.5 vol % of XP-1296;

about 0.025 vol % of 2000 molecular weight polyethylene imine (PEI);

deionized water; and

potassium hydroxide to provide a pH of about 5.75.

Example 3

about 5.1 vol % of phosphoric acid;

about 2 wt. % of ammonium citrate;

about 0.3 wt. % of benzotriazole;

about 0.5 vol % of XP-1296;

about 0.5 vol % of Compound S-900;

deionized water; and

potassium hydroxide to provide a pH of about 5.75.

Examples of multi-step polishing processes include:

Example 1

A copper plated substrate with 300 mm diameter was polished andplanarized using the following polishing composition within a modifiedcell on a REFLEXION® system, available from Applied Materials, Inc. ofSanta Clara, Calif. A substrate having a copper layer of about 11,500 Åthick on the substrate surface with a step height of about 6,000 Å wasplaced onto the first platen and exposed to a polishing composition of:

-   -   about 6% by volume phosphoric acid (85% aqueous solution);    -   about 2% by volume ethylenediamine;    -   about 2% by weight ammonium citrate;    -   about 0.3% by weight benzotriazole;    -   between about 2% and about 6% by volume 40% KOH solution to        provide a pH of about 5;    -   about 1.5% by volume of hydrogen peroxide (30% aqueous solution,        for about 0.45 vol % hydrogen peroxide);    -   about 0.15% by weight of silica (SiO₂) abrasive particles; and    -   de-ionized water.

The substrate was contacted with the first polishing article at a firstcontact pressure of about 0.3 psi, a first platen rotational rate ofabout 7 rpm, a first carrier head rotational rate of about 23 rpm and afirst bias of about 3 volts was applied during the process. Thesubstrate was polished and examined. The copper layer thickness wasreduced and about 1,500 Å.

The substrate was transferred to over a second platen having a secondpolishing article disposed thereon. A second polishing composition wassupplied to the platen at a rate of about 300 mL/min, and the secondpolishing composition comprising:

-   -   about 5.1 vol % of phosphoric acid;    -   about 2 wt. % of ammonium citrate;    -   about 0.3 wt. % of benzotriazole;    -   about 0.5 vol % of XP-1296;    -   about 0.025 vol % of 750000 molecular weight polyethylenimine        (PEI);    -   potassium hydroxide to provide a pH of about 5.75; and    -   de-ionized water.

The substrate was contacted with the second polishing article at asecond contact pressure of about 0.3 psi, a second platen rotationalrate of about 20 rpm, a second carrier head rotational rate of about 21rpm and a second bias of about 2.0 volts was applied during the process.The substrate was polished and examined. The excess copper layerformerly on the substrate surface was removed to leave behind thebarrier layer and the copper trench.

Example 2

A copper plated substrate with 300 mm diameter was polished andplanarized using the following polishing composition within a modifiedcell on a REFLEXION® system, available from Applied Materials, Inc. ofSanta Clara, Calif. A substrate having a copper layer of about 11,500 Åthick on the substrate surface with a step height of about 6,000 Å wasplaced onto the first platen and exposed to a polishing composition of:

-   -   about 6% by volume phosphoric acid (85% aqueous solution);    -   about 2% by volume ethylenediamine;    -   about 2% by weight ammonium citrate;    -   about 0.3% by weight benzotriazole;    -   between about 2% and about 6% by volume 40% KOH solution to        provide a pH of about 5;    -   about 1.5% by volume of hydrogen peroxide (30% aqueous solution,        for about 0.45 vol % hydrogen peroxide);    -   about 0.15% by weight of silica (SiO₂) abrasive particles; and    -   de-ionized water.

The substrate was contacted with the first polishing article at a firstcontact pressure of about 0.3 psi, a first platen rotational rate ofabout 7 rpm, a first carrier head rotational rate of about 23 rpm and afirst bias of about 3 volts was applied during the process. Thesubstrate was polished and examined. The copper layer thickness wasreduced and about 1,500 Å.

The substrate was transferred to over a second platen having a secondpolishing article disposed thereon. A second polishing composition wassupplied to the platen at a rate of about 300 mL/min, and the secondpolishing composition comprising:

-   -   about 5.1 vol % of phosphoric acid;    -   about 2 wt. % of ammonium citrate;    -   about 0.3 wt. % of benzotriazole;    -   about 0.5 vol % of XP-1296;    -   about 0.025 vol % of 2000 molecular weight polyethylene imine        (PEI);    -   potassium hydroxide to provide a pH of about 5.75; and    -   de-ionized water.

The substrate was contacted with the second polishing article at asecond contact pressure of about 0.3 psi, a second platen rotationalrate of about 20 rpm, a second carrier head rotational rate of about 21rpm and a second bias of about 2.0 volts was applied during the process.The substrate was polished and examined. The excess copper layerformerly on the substrate surface was removed to leave behind thebarrier layer and the copper trench.

Example 3

A copper plated substrate with 300 mm diameter was polished andplanarized using the following polishing composition within a modifiedcell on a REFLEXION® system, available from Applied Materials, Inc. ofSanta Clara, Calif. A substrate having a copper layer of about 11,500 Åthick on the substrate surface with a step height of about 6,000 Å wasplaced onto the first platen and exposed to a polishing composition of:

-   -   about 6% by volume phosphoric acid (85% aqueous solution);    -   about 2% by volume ethylenediamine;    -   about 2% by weight ammonium citrate;    -   about 0.3% by weight benzotriazole;    -   between about 2% and about 6% by volume 40% KOH solution to        provide a pH of about 5;    -   about 1.5% by volume of hydrogen peroxide (30% aqueous solution,        for about 0.45 vol % hydrogen peroxide);    -   about 0.15% by weight of silica (SiO₂) abrasive particles; and    -   de-ionized water.

The substrate was contacted with the first polishing article at a firstcontact pressure of about 0.3 psi, a first platen rotational rate ofabout 7 rpm, a first carrier head rotational rate of about 23 rpm and afirst bias of about 3 volts was applied during the process. Thesubstrate was polished and examined. The copper layer thickness wasreduced and about 1,500 Å.

The substrate was transferred to over a second platen having a secondpolishing article disposed thereon. A second polishing composition wassupplied to the platen at a rate of about 300 mL/min, and the secondpolishing composition comprising:

-   -   about 5.1 vol % of phosphoric acid;    -   about 2 wt. % of ammonium citrate;    -   about 0.3 wt. % of benzotriazole;    -   about 0.5 vol. % of XP-1296;    -   about 0.5 vol % of Compound S-900;    -   potassium hydroxide to provide a pH of about 5.75; and    -   de-ionized water.

The substrate was contacted with the second polishing article at asecond contact pressure of about 0.3 psi, a second platen rotationalrate of about 20 rpm, a second carrier head rotational rate of about 21rpm and a second bias of about 2.0 volts was applied during the process.The substrate was polished and examined. The excess copper layerformerly on the substrate surface was removed to leave behind thebarrier layer and the copper trench.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method of processing a substrate, comprising: disposing a substratehaving a conductive material layer formed thereon in a process apparatuscomprising a first electrode and a second electrode, wherein thesubstrate is in electrical contact with the second electrode; providinga polishing composition between the first electrode and the substrate,wherein the polishing composition initially comprises: an acid basedelectrolyte system; a chelating agent; a corrosion inhibitor; apassivating polymeric material; a basic pH adjusting agent in an amountsufficient to provide a pH between about 3 and about 10; and a solvent;and contacting the substrate to a polishing article; providing relativemotion between the substrate and the polishing article; applying a biasbetween the first electrode and the second electrode; and removingconductive material from the substrate surface.
 2. The method of claim1, wherein the contacting the substrate to a polishing article comprisesapplying a pressure between the substrate and the polishing article ofbetween about 0.1 psi and about 1 psi and the providing relative motioncomprises rotating the polishing article between about 1 rpm and about80 rpm and rotating the substrate article between about 1 rpm and about80 rpm.
 3. The method of claim 1, wherein the applying the biascomprises applying a current density between about 3 mA/cm² and about 20mA/cm² to the substrate.
 4. The method of claim 3, wherein the applyingthe bias comprises applying a bias between about 1.5 volts and about 3volts between the first and second electrodes.
 5. The method of claim 1,wherein the composition comprises: between about 1 vol % and about 10vol % of the acid based electrolyte; between about 0.1 wt % and about 6wt % of the chelating agent; between about 0.01 wt. % and about 1 wt. %of the corrosion inhibitor; between about 0.001 vol % and about 2 vol %of the passivating polymeric material; between about 1 wt. % and about20 wt. % of the basic pH adjusting agent; and water; wherein the basicpH adjusting agent is added in an amount sufficient to provide a pHbetween about 4 and less than about
 7. 6. The method of claim 5, whereinthe composition further comprises about 0.5% by weight of a secondpassivating polymeric material.
 7. The method of claim 1, wherein thecomposition further comprises an oxidizer, abrasive particles, orcombinations thereof.
 8. The method of claim 1, wherein the passivatingpolymeric material.
 9. A method of processing a substrate having aconductive material layer disposed thereon, comprising: providing thesubstrate to a process apparatus; exposing the substrate to a firstpolishing composition; contacting the substrate to a polishing article;providing relative motion between the substrate and the polishingarticle; applying a first bias to the substrate; removing at least 50%of the conductive material layer; exposing the substrate to a secondpolishing composition initially comprising: an acid based electrolyte; achelating agent; a corrosion inhibitor; a passivating polymericmaterial; a basic pH adjusting agent in an amount sufficient to providea pH between about 3 and about 10; and a solvent; and contacting thesubstrate to the polishing article; providing relative motion betweenthe substrate and the polishing article; applying a second bias to thesubstrate; and removing the conductive layer.
 10. The method of claim 9,wherein the conductive material layer comprises copper or a copperalloy.
 11. The method of claim 9, wherein the first polishingcomposition comprises: between about 1 wt % and about 10 wt % ofphosphoric acid; between about 0.1 wt % and about 6 wt % of at least onechelating agent; between about 0.01 wt % and about 1 wt % of a corrosioninhibitor; between about 0.5 wt % and about 10 wt % of a salt; betweenabout 0.2 wt % and about 5 wt % of an oxidizer; between about 0.05 wt %and about 1 wt % of an abrasive particulates; deionized water; and atleast one pH adjusting agent to provide a pH between about 4 and about7.
 12. The method of claim 9 wherein the contacting the substrate to apolishing article comprises applying a pressure between the substrateand the polishing article of between about 0.1 psi and about 1 psi andthe providing relative motion comprises rotating the polishing articlebetween about 1 rpm and about 80 rpm and rotating the substrate betweenabout 1 rpm and about 80 rpm.
 13. The method of claim 9, wherein theapplying the first bias comprises applying a bias between about 2.6volts and about 3.5 volts between the first and second electrodes andthe applying the second bias comprises applying a bias between about 1.5volts and about 3 volts between the first and second electrodes.
 14. Themethod of claim 9, wherein the second composition comprises: betweenabout 1 vol % and about 10 vol % of the acid based electrolyte; betweenabout 0.1 vol % and about 6 vol % of the chelating agent; between about0.01 wt. % and about 1 wt. % of the corrosion inhibitor; between about0.01 vol % and about 2 vol % of the passivating polymeric material;between about 1 wt. % and about 20 wt. % of the basic pH adjustingagent; and a solvent; wherein the basic pH adjusting agent is added inan amount sufficient to provide a pH between about 4 and less than about7.
 15. The method of claim 14, wherein the second composition initiallycomprises: about 5.1% by volume phosphoric acid; about 2% by weightammonium citrate; about 0.3% by weight of benzotriazole; about 0.025% byvolume of 750000 molecular weight polyetheyleneimine; sufficientpotassium hydroxide to provide a pH of about 5.75; and deionized water.16. The method of claim 15, wherein the second composition furthercomprises about 0.5% by weight of a second passivating polymericmaterial.
 17. The method of claim 9, wherein the composition furthercomprises an oxidizer, abrasive particles, or combinations thereof. 18.The method of claim 9, wherein the passivating polymeric materialcomprises a polymeric material having a functional group containing anitrogen atom, an oxygen atom, or a combination thereof, and is selectedfrom the group of polyethylene glycol, polyethylene imine, polyamines,and combinations thereof.
 19. A method of processing a substrate,comprising: disposing a substrate having a conductive material layerformed thereon in a process apparatus comprising a first electrode and asecond electrode, wherein the substrate is in electrical contact withthe second electrode; providing a polishing composition between thefirst electrode and the substrate wherein the polishing compositioninitially comprises: about 5.1% by volume phosphoric acid; about 2% byweight ammonium citrate; about 0.3% by weight of benzotriazole; about0.025% by volume of 750000 molecular weight polyetheyleneimine;potassium hydroxide to provide a pH of about 5.75; and the remainderdeionized water; contacting the substrate to a polishing article;providing relative motion between the substrate and the polishingarticle; applying a bias between the first electrode and the secondelectrode; and removing conductive material from the substrate surface.20. The method of claim 19, wherein the polishing composition furthercomprises about 0.5% by weight of a second passivating polymericmaterial.